Mobile coupon usage is still catching on. Just 16.3% of the country’s mobile phone users redeemed a mobile coupon in the US in 2012. But adoption of this money-saving activity is expected to expand substantially in the next few years. The number of US mobile coupon users will rise from 12.3 million in 2010 to 53.2 million in 2014, driven by the rapid adoption of smartphones. By 2014, one in four mobile phone users will redeem a coupon via a mobile device. Read the rest at eMarketer.