Examining smart phone shipments by OS provides another glimpse into Nokia’s decline. According to Q2 2011 and Q2 2012 shipment data by the Internatioanl Data Corporation’s (IDC) “Worldwide Mobile Phone Tracker,” Symbian shipped 18 million smart phones in the second quarter of 2011. But one year later, that number had dropped to 6.8 million. This decline aligns with Nokia’s February 2011 announcement that it would transition off the Symbian operating system in favor of Microsoft’s Windows 7 for the Lumia devices. Read the rest at eMarketer.