$585,000 comes out to 0.1778116% (almost two tenths of one percent) of Mozilla's 2015 revenue of $329,000,000.
As an avid Firefox user since 2007, upon learning a few years ago how much revenue Mozilla takes in, I've always wondered where the hundreds of millions of dollars are spent... I was talking with a colleague about Servo, and was saying, "If they spent allocated 5% of that revenue on Servo, they could hire 70 developers year round at $235,000 each to work on Servo full time, year-round."