Nearly half of all U.S. adults who use the Internet will have redeemed an online coupons or discount code by the end of the year, says a new report from eMarketer.

The market research firm says that by Jan. 1, 88.2 million consumers will have used online coupons and codes. That’s 5.5% higher than the 83.6 million consumers who had redeemed the coupons and codes by the end of 2010.

“Consumer brands are accustomed to promoting their products in stores and in newspaper inserts,” says Jeffrey Grau, eMarketer principal analyst. “But as more shoppers make purchase decisions online before taking a shopping trip, brands are following them onto the Internet.”

The research firm says it made its estimates by aggregating and analyzing data from other firms that track online coupon use.

By the end of 2013, eMarketer says, 96.8 million U.S. online adults will have used such discounts, up 15.8% from 2010. But the growth rate in online coupon use them will slow, because by then most consumers who want to use those types of discounts will already be doing so, the report says.