Google’s Andy Rubin announced Tuesday that the number of Android activations has hit 500,000 a day.

In a tweet Rubin said that the number is growing by 4.4 percent week on week, which is rather impressive. Google’s Android OS has been on the market for less than three years, but it has boomed over the past 18 or so months.

Analysts expect Android market will continue to climb in the foreseeable future and the OS should command about 39 percent of the smartphone market by 2015.