Despite high turnout during Black Friday weekend, U.S. shoppers spent an average of 3.5% less than a year ago, the National Retail Federation reported. Consumers spent $289.19 over the four-day weekend compared to $299.60 over the same period in 2015, according to the NRF’s survey of 4,330 consumers. About 154 million people made purchases, up from 151 million a year ago. The survey also found that online sales topped in-store purchases 44% to 40%.

NRF President and CEO Matthew Shay attributed the drop in overall spending to promotions and discounts offered as early as Halloween. "Consumers know they can get good deals throughout the season and these opportunities are not a one-day or one-weekend phenomenon, and that has showed up in shopping plans,” Shay said.

With the data from Black Friday Weekend, the NRF maintained its forecast for retail sales to rise 3.6% to $655.8 billion this holiday season.

Millennials (ages 18-34) drove the increase in shopping, as eight in 10 shoppers made purchases over the weekend. The survey found that 62% of millennials shopped online and 56% went to brick-and-mortar stores. Among all age groups, there was a 4.2% rise in online sales and a 3.7% drop in in-store purchases.

More than one-third of shoppers said all of their purchases were on sale, an amount triple the total from last year.

Department stores had the most shoppers at 51% compared to discount stores (34%), electronics stores (32%), clothing or accessories stores (28%) and grocery/supermarket stores (25%). Apparel and accessories, toys, electronics, books, video games and gift cards were the most popular items, said Pam Goodfellow, principal analyst at Prosper Insights & Analytics, which conducted the survey.

Shay remained optimistic for retailers as data indicates more purchases are coming. Only 9% of consumers have finished their holiday shopping, and more than 23% of consumers have not even started shopping for the season.