Internet marketing research company comScore released its first quarter, 2012 U.S. internet retail sales estimates today, recording a 17% sales increase over last year, totaling roughly $44.3 billion. The latest numbers mark the tenth instance where quarter-over-quarter sales have risen.

comScore cites that in Q1, 2012, digital content and subscriptions, computer software, consumer electronics, jewelry and watches and event tickets were the most popular online product purchases. Also, 48.8% of e-commerce transactions included free shipping, the highest ever outside of a holiday shopping season. During the Q1 period, 38% of tablet users bought something online, with clothing being the most popular items. While its been reported that many retailers lack online storefronts optimized for shopping via a tablet device, U.S. consumers have come to expect a sort of integrated shopping experience, spanning smartphones, tablets, desktops and physical, brick-and-mortar retail storefronts. Online retail for tablet optimization is advancing, and a higher percentage of tablet-based purchases should be expected.

comScore chairman Gian Fulgoni states, “The first quarter of this year was especially strong for retail e-commerce as we returned to year-over-year growth rates in the high teens, numbers we haven’t seen since 2007 – While the economic recovery continues to be painfully slow, the channel shift to e-commerce appears to be accelerating. This presents opportunities but also challenges for brick-and-mortar retailers if they can’t hold onto their offline market share in the digital world.”

An undesired effect of a sort of digital window shopping are instances of consumers using brick-and-mortar showrooms to get a hands-on look at items they’d shopped for online. This practice is one of the reasons why Best Buy has been closing stores. Customers have begun plainly using big box locations as a place to test drive products they plan to buy online anyway, for usually cheaper.