That puts pressure on brick-and-mortar retailers, which count on holiday shopping for up to 40 percent of their annual revenue, to get shoppers into stores. It's becoming an increasingly difficult feat: The National Retail Federation estimates that overall sales in November and December will rise 4.1 percent this year, below last year's 5.6 percent growth. But the online part of that is expected to rise 17 percent, according to research firm comScore."Retailers have to do a little more to grow sales this year," said Frank Badillo, a senior economist at consultancy Kantar Retail. This isn't the first time stores have had to up the ante. As Americans cut back on spending during the economic downturn, merchants ramped up their already deep discounting. Shoppers became addicted to the ever bigger sales, and they began fleeing to online retailers, which can offer much cheaper prices because they don't have the same overhead costs to operate brick-and-mortar locations. Plus, websites offer the convenience of shopping in the comfort of homes or office cubicles. To better compete, brick-and-mortar stores concluded that they would have to replicate their online rivals' formula. Shopping needs to be cheap and easy, they figured. So stores began trying new ways to make shopping more convenient last year, such as free shipping and expanded hours. This holiday season, they've expanded the scope and scale of those incentives to include: â¿¿ EXPANDED HOURS FOR SHOPPERS WHO CAN'T WAIT TO HIT THE MALL: Stores often open in the wee hours of the morning on the day after Thanksgiving Day, which is typically the biggest shopping day of the year. But the Black Friday openings crept earlier and earlier over the past few years. Then retailers such as Macy's Inc. began opening at midnight. This season, some stores have expanded their hours even more. Sears, Toys R Us and other stores are opening on Thanksgiving evening to grab those who want to shop after their turkey dinner. Wal-Mart is starting Black Friday sales at 8 p.m. Thanksgiving Day, two hours earlier than last year.