Employees push trolleys on the warehouse floor at an Amazon.com Inc. fulfillment center in Koblenz, Germany, on Tuesday, Nov. 29, 2016. E-commerce sales in November and December will grow 17.2 percent to $94.7 billion, more than five times the pace of total retail sales growth of 3.3 percent, according to EMarketer. Photographer: Martin Leissl/Bloomberg via Getty Images