Join us each Monday on the comScore Data Mine for Mobile Mondays – featuring the latest insights into mobile usage across geographies. Follow the “Mobile Mondays” tag to see these gems. Smartphone usage continues to grow across the U.S. with 72.5 million people owning a smartphone in March 2011. Google Android accounted for 34.7% market share, while RIM ranked second with 27.1%. Apple accounted for 25.5% share, followed by Microsoft (7.5%) and Palm (2.8%).