There is a lot of hype around Facebook filing to become a public company. One interesting number that arose during their IPO filing on Wednesday is that Zynga accounts for 12% of all of the revenue generated by Facebook. Facebook’s sales for 2011 totaled at $3.71 billion and $445 million of that revenue came from their current partnership with the game-maker Zynga. The independence of the two companies may become an issue for investors. Learn more about these two companies by visiting Mashable.