This is going to be a very difficult question to answer, though I've often, as a Classicist, wondered something similar myself. The only way to really quantify in a way you are wanting would be by "word count," which is itself problematic (Greek has articles and particles, for instance, which inflate its word count vs Latin in the long term). On Perseus reports 13 million Greek words in its collection, and 10 million Latin words. This probably translates to about the same amount of "text," give or take. There is also the problem of chronology and content. We have Greek texts from the 7th century BCE all the way to the late Medieval period. Which are included? We have many texts which are very fragmentary. Are they included? Still, Perseus has a pretty good coverage of the "core" or "canon" ancient texts, and we are fortunate that it has a word count. It's good enough to use as comparison, anyway. Now you would need to find a word count for, say, Sanskrit within a bounded time-frame. Good luck with that!