This chart shows US funding of tech companies since 1980, adjusted for inflation (it's an updated version of one we included as part of a long study here).
First, on definitions: the number of IPOs has collapsed since the early 2000s, for a variety of reasons, and in parallel a large part of later stage funding of high-growth tech companies has moved from the public to private markets. That is, companies that would have done an IPO now do private growth rounds instead. A lot of the investors taking part in these rounds are not venture-capital, but hedge funds, private equity firms and even conventional public market investors. Hence, it's not very meaningful to look just at 'private' funding, or even to call that 'VC' - you have to look at the total funding picture.
Second, 2015 annualized funding is up. The increase from 2014 to 2015, though, is nothing like the explosion in 1999.
Third, and most important - since 1999 there are now roughly 10x more people online, US online revenues from ecommerce and advertising have risen 15x, and the cost of creating software companies has fallen by roughly 10x.