WASHINGTON ( AP) — Retail sales barely rose in December, but the gain was enough to lift sales to a record level for 2011. It marked the largest annual increase in more than a decade.

Sales inched up 0.1 percent in December to a seasonally adjusted $400.6 billion, The Commerce Department said today. It was the second straight month that sales have topped $ 400 billion. Never before had monthly sales reached that level.

The government revised the November sales to show a stronger 0.4 percent gain — twice the original estimate. That pushed sales in November above $400 billion on a seasonally adjusted basis.

For all of 2011, sales totaled a record $4.7 trillion, a gain of nearly 8 percent over 2010. It was the largest percentage increase since 1999

Steady sales gains have fueled a 20 percent surge from the low during the recession. Monthly sales are 6 percent above their pre-recession high.

The figures confirm evidence that the economy was strengthening as 2011 ended.

One caveat: Many retailers said they had to offer steep discounts in December to attract holiday shoppers.

Those discounts showed up in weaker department store sales. They fell 0.2 percent in December. A broader category that includes department stores like Macy’s and big chains such as Wal-Mart and Target showed an even larger decline last month: 0.8 percent.

The strength last month was led by a 1.5 percent jump in auto sales. Furniture store sales rose 1 percent. Hardware stores reported a 1.6 percent increase. But sales at electronics and appliance stores sank nearly 4 percent.

Sales at gasoline stations fell 1.6 percent. That decline reflected mainly lower gas prices. Excluding gas stations, retail sales would have risen 0.3 percent in December.