I can't find any figures, and after learning about Allied troops' rape of thousands, I'm curious. Death tolls are given, but not rape tolls.
Part 1
Oh man, what a question...
It's impossible to give a definitive answer to this question beyond estimates based on what evidence we have available but these always remain estimates rather than hard, concrete numbers.
This is due to a variety of reasons:
As every criminologist and sociologist dealing with the matter will tell you, rape is one of the most under reported crimes there are for a variety of reasons, chief among them social stigmatization of the victim and social discourse on sexual violence. Recent studies estimate that only 4-5% of all occurring rapes are reported in the US. For historical societies we are forced to assume the same or an even worse number in terms of reports, more likely worse given historical discourse in the 1940s on the issue. So, reviewing the number of historically reported instances of rape will only ever represent a tiny fraction of all rapes that occurred.
Rape is defined broadly as sexual intercourse without consent of one party. That seems pretty straightforward at first, but the question of consent always involves the context of the relationship between the parties involved. Various lawmakers around the world have introduced laws akin to a statutory rape statute that protects those who can not legally give consent but also offers particular protection to persons in a relationship of dependency because they assume a higher thread of potential coercion in such relationships.
Now, when we review the historical context of a liberating and occupying army coming to a territory, this issue becomes a bit difficult in that the relationship between two parties in such a situation is almost never equal. On the one hand you have an army of men with weapons who replace law and order in whatever territory someone lives in. On the other hand you have a population that is in their interaction with the former group very much at the personal mercy of whatever armed member of an occupying army they encounter. Such a relationship is by its very definition unequal and thus the issue of consent – which assumes adults of sound mind and of basically equal relationship to make an informed decision about whether they want to engage in intercourse – becomes muddled.
Consider, a women in a country that not only lost a lot if its men in a war but where public order has broken down and completely or partially replaced by an armed occupation is talked into intercourse by a member of the occupying army based on the impression he conveys to her that she needs a protector from other soldiers. Can we in such a relationship where one party holds the potential power over life and death of the other party, whether they use it consciously or subconsciously, assume that consent can even exist? Can this hypothetical woman even make a decision that is not based on implicit or explicit coercion by her hypothetical partner?
I have previously mentioned the social stigma attached to sexual violence, which is exacerbated by the fact that within this context, the Allied armies came as liberators from Nazism and especially in the case of German women, they were viewed by occupiers and historians alike as part of a group of perpetrators at worst. This form of bias is displayed in that there were very early attempts to establish facts about the sexual violence excreted by the Red Army but little done in regards to the Western Allies. With the Red Army it fitted the narrative and the rate of incidences of sexual violence committed by them was much higher than with Western Allies. The convergence of these two factors leads to the current situation where we have a clearer (although not entirely clear for reasons stated above picture) of the sexual violence committed by members of the Red Army in WWII than in the case of other armies.
In a similar vein, historians who would have had the chance to establish a clearer picture in general through techniques such as interviews with victims did not do so because the issue of sexual violence and the stigma attached to it lead to it being ignored for a very long time by many a historian. It was and in part remains a topic inconvenient on some level in both academia and history politics.
With this preamble on the difficulty of researching the topic in mind, the current consensus on sexual violence and rape in WWII is that it albeit it was not part of military strategy like we are able to observe in such wars like the Yugoslav wars of the 90s, it was incredibly prevalent and the numbers of incidents of sexual violence and rape are in the millions.
Atina Grossmann discussing the book BeFreier and Befreite by Helke Sander and Barbara Johr writes:
But hard - or even soft - facts are hard to come by and unreliable. It has been suggested that perhaps one out of every three of about one and a half million women in Berlin at the end of the war were raped - many but certainly not all during the notorious week of "mass rapes," from April 24 to May 5, 1945, as the Soviets finally secured Berlin. The numbers cited for Berlin vary wildly; from 20,000 to 100,000,to almost one million,with the actual number of rapes higher because many women were attacked repeatedly. Sander and her collaborator, Barbara Johr speak, perhaps conservatively, of about 110,000 women raped,many more than once,of whom up to 10,000 died in the aftermath. At the same time- and despite their virtual fetishization of statistical clarity - they announce on the basis of Hochrechnungen (projections or estimations) that 1.9 million German women altogether were raped at the end of the war by Red Army soldiers.
In terms of numbers, Anthony Beevor has come to a similar estimate for the Red Army with 1.8 million rapes in Germany territory.