[jliechti1]

The rule of thumb among VCs is about 15 per year. Assuming $100+ million is considered a "big success". The cap for big success might be higher.

See more here: http://www.paulgraham.com/invtrend.html

Actually, this article here has some good quantitative data. It puts the number around 200. It looks like most of the companies are non-tech/outside the Valley though.

http://bostinno.streetwise.co/2013/05/14/only-200-startups-p...

[ramanujan]

I believe the rule of thumb is that there are 15 that reach $100M revenue. We could square the figure of 200 at $100M valuation with this rule of thumb if we assume valuation is say 10X revenue, so 200 reach ~$10M revenue. Thus maybe 1/15 or so of the companies that reach $10M in revenue hit the next level of scale and get to $100M revenue.