Apparel sales are benefiting from millennials, the strength of the athleisure category and the growth of e-commerce, but those factors weakened last year, according to a report from The NPD Group emailed to Retail Dive. U.S. apparel sales last year fell 2% year over year to $215 billion, according to the report. In 2017, millennials contributed the highest apparel growth rate of all generations at 4%, (or $2 billion in incremental sales), NPD found. But last year that slowed from the double-digit increases seen over the previous two years, according to the report. And while non-activewear sales declined as activewear sales grew in 2017, last year’s rise wasn’t as steep as it has been: Activewear sales rose 2% to $48 billion (22% of total apparel sales). Finally, while e-commerce remains a “driving force” in apparel sales, considering the decline of apparel sales in physical stores, those stores retain more than three-quarters of annual apparel dollars, according to Slice Intelligence data cited by NPD. The purchase frequency of online apparel consumers increased last year, but they spent 5% less per receipt, according to that research. Read more at Retail Dive.