In the fourth quarter, U.S. e-commerce sales grew 14.3% to $123.61 billion from $108.18 billion. The growth rate for Q4 is the smallest year-over-year increase since the fourth quarter of 2014, when online retail sales grew 13.9%.

Still, online sales are growing much faster than store sales, which suggests that e-commerce remains a primary growth driver in the retail industry as a whole.

Total retail sales reached $1.30 trillion in the fourth quarter, a 3.9% increase compared with $1.25 trillion in Q4 of 2015. When factoring out the sale of items not normally bought online, like automobiles, fuel, and bar and restaurant sales, total retail sales reached $929.25 billion, a 3.3% jump compared with $899.46 billion in the same period a year ago.

That suggests e-commerce represented 13.3% of total retail sales in Q4 compared with 12.0% in Q4 of 2015.