Firfox launched on November 9, 2004. It took one year for Firfox to reach 100 million downloads. One further year and it doubled to 200 million. One more year and it’s doubled again to 400 million downloads.

Mozilla estimates that approximately half of the users who download Firfox never install it, and half of those who install it don’t become permanent users. Although this is actually a pretty decent retention rate for a software program that can be downloaded for free on the Internet, it is still a point that Mozilla is working hard to address. Full article