Although ecommerce sales will account for just 6.4% of the $4.73 trillion in total U.S. retail sales expected this year, the true impact will be much bigger, according to a new eMarketer report. Of the 219.4 million internet users in the U.S. 14 and older, eMarketer expects 196.6 million, or 89.6%, to shop online this year, compared with 163.2 million who will go on to complete a purchase digitally.