The total value of Y Combinator companies is now over $3 billion
techcrunch.com
techcrunch.com
You could break it down by year, but then you're into such small numbers of actual companies, with such a wide range of current valuations from zero to many millions, that it's an even less useful metric.
I'd be shocked if any other incubator even came close with any comparative measure though.
It's not all the fun and Benjamins some people crack it up to be.
Care to elaborate?