In its annual State of the Appnation report, Nielsen reports that 50% of U.S. mobile subscribers use smartphones, which is up from 40% in 2011. Much of the growth in mobile apps has come directly from the growth of Android and iOS users, which more than doubled from 38 million in 2011 to 84 million in 2012. Today, 88% of Americans who have downloaded a mobile app in the 30 days prior to the Nielsen survey, indicated that they used an Andriod or iOS smartphone to do so (up from 74% in 2011).The number of apps per smartphone is rising quickly, too. According to the Nielsen study, the number of apps per smartphone averages 41 in 2012. That's a 28% leap from 32 apps per smartphone in 2011. The time spent using mobile apps has also grown by 10% between 2011 and 2012. You can see the data from the study in the image from Nielsen below. Here are some highlights:

• Proportion of time spent on the top 50 apps decreased from 74% in 2011 to 58% in 2012.
• Overall time spent using apps remained relatively flat from 2011 (37 minutes per day) to 2012 (39 minutes per day).
• Time spent on apps vs. web increased from 73% in 2011 to 81% in 2012.
• Top five apps in 2011 and 2012 are the same: Facebook, YouTube, Android Market (now Google Play), Google Search, and Gmail.
• Privacy matters to mobile consumers with 70% expressing concerns about privacy and personal data collection in 2011 and 73% expressing the same concerns in 2012.
• Half of American smartphone users (55%) are concerned about sharing information about their locations when using smartphone apps.

As the data from Nielsen demonstrates, there is still a lot of growth for the mobile app industry. It will be interesting to see the State of the Appnation report in 2013!Image: Nielsen