"Android developers are significantly more productive than Apple's," said .

The research firm noted, though, that more apps are later removed from than from the App Store, for various reasons.

Apple still attracts more apps to its store.

The higher average for Android developers led to a total number of apps submitted on Android Market of more than 500,000 in September. At the same time, the number of apps submitted to the App Store reached more than 600,000, or 20% more.

The analyst firm noted the fast growth of Android Market, which is roughly a year younger than the App Store.