According to a new survey by comScore, the number of U.S. smartphone users averaged 74.6 million from February through April -- a 13 percent rise from the previous three months. The web-metrics firm also reported that 234 million Americans over the age of 12 were using mobile devices. amsphone.com U.S. carriers AT&T and T-Mobile are hoping to drive smartphone demand even higher with new smartphones that carry post-rebate prices in the $70 to $80 range. However, industry analysts said all U.S. carriers still need to do more to encourage consumers to switch from standard cell phones to smartphones. "Introductory limited-data plans of $10 to $15 a month will expand the market greatly for these devices, and in many cases consumers will upgrade to higher-priced data plans over time once they get hooked on these services," said Hugues de la Vergne, a principal research analyst at Gartner . Android Popularity Rises A survey by Gartner in December showed that U.S. consumers are more likely to buy a smartphone this year than PCs, mobile phones, e-readers, media tablets, and gaming products. Gartner expects U.S. smartphone sales this year to total 95 million -- up from 67 million in 2010. "As vendors delivering Android-based devices continue to fight for market share , prices will decrease to further benefit consumers," said Roberta Cozza, a principal analyst at Gartner. amsphone.com In comScore's latest survey, Google 's Android operating system led the smartphone segment with a 36.4 market share -- up 5.2 percentage points from the firm's previous three-month study. Gartner expects Android to become the most popular operating system worldwide by the end of this year. "Android's position at the high end of the market will remain strong, but its greatest volume opportunity in the longer term will be in mid- to low-cost smartphones -- above all, in emerging markets," Cozza said. Although comScore's report of 74.6 million U.S. smartphone users is huge, a significant number of these devices were provided by enterprises to their employees, with the percentage of corporate smartphones varying by company. "Many support very few," noted Lisa Pierce, an independent wireless analyst at the Strategic Networks Group. "But for those with active corporate-liable policies, the percentage of mobile employees covered by corporate-liable -- versus individually liable -- contracts averages between 18 percent and 34 percent."