I would say the vast majority. For consumer web startups, you can just guess just by looking at their Compete traffic stats (comparing # of unique visitors to # of employees). For enterprise, it gets a little trickier, but if you see some big client names in their homepage, you can tell they're profitable by themselves.

Wufoo (Acquired by SurveyMonkey) and Olark have both survived without raising additional funding.

I assume that is what you mean?

I'm wondering if these are the exceptions. I heard something like 98% of YC startups get funding, but how many of them are unprofitable and exist only because of their funding in this bubble period?

Your assumption is that VCs fund YC startups purely because they are YC startups?

My question was not about VC motives. My question is how many YC startups will go bust along with the collapse of the Social bubble.