There are more than 145 companies worth over a billion dollars in Silicon Valley.

Of those, 21 more than doubled their value in the last year.

Venture-capital database CB Insights tracked the list of the biggest unicorn valuation increases of the year. "Unicorn" is Valley parlance for a company worth more than a billion dollars.

Here's the list of companies that more than doubled their value in the past year, courtesy of CB Insights: