Imports at the nation’s major retail container ports grew 7% during 2017 over 2016 as retail sales continued to increase and the industry wrapped up the year with a strong holiday season, according to new Global Port Tracker figures released by the National Retail Federation, a retail trade association, and Hackett Associates, an international maritime consulting, research and advisory firm.

Ports covered by Global Port Tracker handled 1.74 million 20-foot equivalent units (TEUs) in November, the latest month for which after-the-fact numbers are available. With most holiday merchandise already in the country by that point, the number was down 1.7% from October but up 5.8% year-over-year. A TEU is one 20-foot-long cargo container or its equivalent.

December was estimated at 1.6 million TEUs, up 2.6% year-over-year. The total for 2017 is expected to come to 20.1 million TEUs, topping last year’s previous record of 18.8 million TEUs by 7%. That would be more than double 2016’s 3.1% increase over 2015. The year set an all-time monthly record of 1.8 million TEUs in August, and included five of only seven months on record when imports have hit 1.7 million TEUs or higher.

Global Port Tracker covers the U.S. ports of Los Angeles/Long Beach, Oakland, Seattle and Tacoma on the West Coast; New York/New Jersey, Hampton Roads, Charleston, Savannah, Port Everglades and Miami on the East Coast, and Houston on the Gulf Coast.

“Retail had a strong year fueled by growing wages, higher employment and a boost in consumer confidence,” NRF Vice President for Supply Chain and Customs Policy Jonathan Gold said. “Retailers imported more merchandise than ever to meet demand for quality products at affordable prices, and growth is expected to continue in the year ahead.”

January is forecast at 1.68 million TEUs, up 0.2% from January 2017; February at 1.62 million TEUs, up 12.6% from last year; March at 1.5 million TEUs, down 2.3%; April at 1.66 million TEUs, up 3.3%, and May at 1.73 million TEUs, up 0.4%. The February and March percentages are skewed because of changes in when Asian factories close for Lunar New Year each year, according to the report

NRF forecast that 2017 retail sales would grow between 3.2% and 3.8% over 2016 and that holiday sales would grow between 3.6% and 4%, but year-end numbers will not be released by the Commerce Department until Friday, however, other reports released earlier indicated a strong season for retailers.

The group noted that cargo volume does not correlate directly with sales because only the number of containers is counted, not the value of the cargo inside, but nonetheless provides a barometer of retailers’ expectations.

“On a percentage basis, 2017 was one of the strongest increases we’ve seen since the end of the Great Recession,” Hackett Associates Founder Ben Hackett said. “That’s no minor achievement at a time when many are trying to talk down the economy. The rate is expected to slow down some, but with 2017’s performance and continuing high consumer confidence, our models show continued growth in the coming year.”