Another key barometer buttresses a consensus forecast for a 3.8 percent gain in holiday retail sales this year. The holiday season doesn't end until Sunday because of returns, gift card redemptions and post-holiday clearance sale crowds. For the week ending Christmas Eve, sales activity measured by the retail index of the International Council of Shopping Centers slowed, but was still a "solid" 1 percent ahead of last season. With gift card sales well ahead of last year, the results are a harbinger that general merchandise sales are on track for a 3.5 to 4 percent gain, said Mike Niemira, ICSC chief economist. The index tracks actual sales reported by 24 of the largest chains from Costco to Macy's, but not Walmart. The index does not reflect gas, food or auto sales. Largely discretionary spending, holiday sales are a closely watched measure of the nation's economic health because consumer spending is more than two-thirds of the economy. The two-month season also accounts for up to a third of the annual revenue and half the annual profit for many retailers. Meanwhile, ComScore said online general merchandise sales jumped 16 percent to a record $35.2 billion from Nov. 1 through Christmas Day. That would make online retailing about 9 percent of the total.