Many startups raise multiple rounds, so I think you're double counting? Don't you need to either divide 16,464 by the typical number of funding rounds or only count, say, series As?
It wouldn’t be called “IPO” anymore, but a company can offer subsequent market shares through a Follow-on Public Offering (FPO.) This occurs when a business raises capital in a second round of stock through either dilutive or non-dilutive options. Good to know.
(An extreme example to prime your intuition: imagine that there are one IPO and 10 VC deals annually. If every startup raises money annually and there are 10 startups at any one time, then every funded startup eventually IPOs.)
Ignore mine.