Sales at U.S. retailers rose slightly less than expected in December, but retail sales for all of 2010 reversed two years of contraction and posted the biggest gain in more than a decade, a government report showed on Friday.

Total retail sales climbed 0.6 percent, advancing for the sixth straight month as sales declines at electronics and general merchandise stores were offset by gains in gasoline and building materials sales, the Commerce Department said. Analysts polled by Reuters were expecting sales to gain 0.8 percent.

Excluding autos, sales rose 0.5 percent. Analysts had forecast a 0.7 percent increase.

Total sales for the 12 months of 2010 were up 6.65 percent from the previous year after a 6.5 percent drop in 2009. It was the largest 12-month gain in sales since 1999.