Google’s Android Market began 2012 with a big milestone, passing more than 400,000 total applications available worldwide, according to European app tracking company Distimo.

Although Android Market took longer than Apple’s App Store to hit the 400,000 app mark — 39 and 37 months respectively — Android Market’s growth is accelerating faster than its rival’s, according to Distimo. It took Apple’s app store seven months to go from 300,000 to 400,000 apps, but only four months for the Android Market to do the same.

While Android Market may be gaining on iOS for now, findings from Flurry in December showed that for every new app planned for Android, three were in development on iOS.

The issue is that while Android’s reach is now growing faster than iOS in terms of smartphone sales or activations, the platform monetizes about one-fourth as well.

Another interesting trend Distimo found is that the overall percentage of free to paid apps is increasing. When Android Market hit 200,000 apps in April 2011, 60 percent of all apps were free. That number has now increased to 68 percent, largely due to the prevalence of the freemium business model on the platform, which goes hand-in-hand with Android’s lower conversion and monetization rates. As we reported earlier, Android apps typically make 24 cents for every dollar iOS apps do. Developers are far more likely to make their apps free and rely on advertising for revenue.

Distimo also found that while Google now has more than 100,000 active developers for its platform, the average number of apps published per developer has dropped. A year ago an Android developer published an average of five apps, but now the average is 4.1 apps.

At the beginning of December, Android Market passed another milestone, its 10 billionth app download. Consumers are now activating more than 700,000 Android devices a day.