These 15 startups didn't exist 5 years ago — now they're worth billions

Silicon Valley can create immense value in just a short time. Just look at these 15 startups that didn't even exist five years ago, which are now valued at $1 billion or more, according to venture capitalists. 
For the purposes of this list, Business Insider asked PitchBook Data to pull a list of US-based companies that were founded in 2012 or later — since we're nearing the end of 2016 — and that are private tech companies with a valuation of north of $1 billion. 
We then