Quite a lot, actually. While some startups (e.g. Twitter) take a while to generate significant revenues, it happens that the most successful startups we've funded were not of that type.

I'm curious what proportion of YC's success has come through very public, consumer-facing companies like Reddit, vs. companies the outside world never hears of, that quietly make tons of money behind the scenes selling to businesses and/or governments.

I'd still like to know the exact figure. its easy to find out how much was put in, but not so easy how much was generated. I'd love to know the total yc bottom line.

For whom? As I understand it, quite a bit of that "raised" money ends up in the pockets of earlier investors.