it's very hard to answer this question in a lot of cases due to the covert aspect of assassination or overthrow.
the one I have the most depth in is Patrice Lumumba's overthrow, orchestrated by Joseph-Desire Mobutu (then head of the Armee National Congolais) and Moise Tshombe (leader of the secessionist movement in the mineral-rich region of Katanga). while sources vary in their assessment, there are allegations (and indeed claims on behalf of certain American elements) of Belgian and American support/funding/participation for the coup d'etat. in fact, Belgian gendarmes may have actually participated in the murder of Lumumba. whether or not the CIA was actively involved is still a matter of debate to this day.
however, if you consult Lawrence Devlin's Chief of Station Congo: Fighting the Cold War in a Hot Zone, the former Station Chief claims that he had direct orders to carry out an assassination on Lumumba should he see fit. he was equipped with poison and various other methods to execute the killing. Madeleine Kalb's The Congo Cables also hints at CIA inclusion, with her main sources being diplomats and politicians from Belgium, UK, France, and the US. neither are really conclusive but ultimately the CIA at least knew what was going on, whether or not they actually were involved.
importantly, on the topic of business interests, the Lumumba case is quite interesting. as another commenter stated, you can never really separate business interests and political interests. especially in this case, the removal of Lumumba ("a castro or worse" in the words of Allen Dulles) was certainly a Cold War imperative but also had direct links to the substantial British, Belgian, and French mining interests in the provinces of Katanga and Kasai (Orientale to a lesser extent). within the purview of David Gibbs (The Political Economy of Third World Intervention) this was directly linked to the necessity of a unified and strong NATO alliance, of which all three were integral partners. this meant deferring to them in the Third World, especially when it concerned economic well-being (both for the nations independently and in maintaining an international capitalist economic order). John Kent's America, the UN and Decolonization argues in a similar vein. finally, though she sees the Cold War context as more important, Lise Namikas' Battleground Africa also supports the need to understand economic motivations.
thus while we can't connect the US to direct support for the coup d'etat (we can, on the other hand, find the receipts for CIA support for Mobutu, the principal actor in the assassination), they did undermine Lumumba and support his major opponents (Moise Tshombe included). this line of policy was certainly related to the substantial business interests in mining regions of the Congo. however, they were always framing the Congo Crisis within a Cold War prism, so it's very difficult to overlook political motivations in our pursuit of economic explanations.
PS: the Church Committee highlighted the Lumumba case but only the attempt on his life by way of poisoning, mentioned previously. there was never a direct connection to the actual coup d'etat. as someone who studies the Congo, I've seen most of the US documents and they are heavily censored. we'll undoubtedly need to wait quite a while to really get a sense for what happened, if we ever do. my personal feeling is that the US probably only supported the coup from afar and didn't have a direct hand in the actual murder. that doesn't mean they didn't overthrow the government, it's just hard to call it an assassination.
How many leaders (democratic or not) did the us overthrow overall?
This question doesn't really fit the rules on specificity for this subreddit, but it is still an interesting question. Taken as a whole, economic interests were the leading driver of American foreign policy throughout the 20th century.^1 During that time, American power was used to influence many foreign governments in multiple ways.
The short answer to your question is to just say, in every case that the US "overthrew a democratically elected foreign leader", the US did so at least in part for economic reasons. You could say that every foreign policy decision of the last century was at least in part influenced by business interests.
But the question becomes much more complicated when you have to define "democratic" and "overthrow". For example, the 1949 Syrian coup d'etat against their republican government was executed by a military leader, Husni al-Za'im, within Syria.^2 It is known that al-Za'im met with the American Central Intelligence Agency (CIA) several times to discuss the plans to seize power. Although it isn't clear if the CIA provided material support for the coup, after seizing power the al-Za'im government approved the Trans-Arabian Pipeline, an American project that had been stalled under the previous government. Would this count as an American overthrow of a democratically elected leader?
As you might be able to see, answering your question requires not just an expert understanding of the history but also a strong opinion on each individual case. It's too broad of a question for a specific answer.
So the best answer, again, is to just say that US foreign policy is driven by economic interests, that all actions by the US to influence or affect change within foreign governments are at least in-part affected by business interests, and that the US has broad powers in the foreign policy arena that it exercises regularly.
Combs, Jerald A. The History of American Foreign Policy. 3rd ed. Armonk, N.Y.: M.E. Sharpe, 2008. 177-178. https://books.google.com/books?id=4YIBMXcZnxsC&lpg=PA21&pg=PA177#v=onepage&q&f=false. "The dilemma Wilson, Taft, and Roosevelt faced is still with us and still generates controversy. Revisionists condemn America's historic policies toward Latin America in toto. Like the Latin American Left itself, they believe that the United States intervened in Latin America promarily for economic gain, to protect and increase American trade and investments. American interventions were not motivated by fears for national security,because no outside power posed a credible threat to Latin America after the British retreated at the turn of the century. The United States intervened instead to perpetuate the dictatorship of the Latin American upper classes, which were allied with the economic interests of the United States. It sought to protect its collaborators against indigenous revolutionaries who had no choice but to seek nationalization of land and resources because wealth was concentrated in so few hands. Obviously, the United States had no interest in democracy or it would have supported such revolutionary movements.".
Gendzier, Irene. Notes from the Minefield: United States Intervention in Lebanon and the Middle East, 1945–1958. Columbia University Press. 1997. p. 98. "Recent investigation... indicates that CIA agents Miles Copeland and Stephen Meade... were directly involved in the coup in which Syrian colonel Husni Za'im seized power. According to then former CIA agent Wilbur Eveland, the coup was carried out in order to obtain Syrian ratification of TAPLINE."
I'm the OP. I was really wondering how many democratic leaders were overthrown to protect US financial interests. Like what we saw in Chile when the US government overthrew a democratic leader to install a dictator who would look out for our private business interests.