WASHINGTON -- U.S. home prices rose at a healthy pace in December compared with a year ago, driven higher by rising sales and a smaller supply of available homes.

The Standard & Poor's/Case-Shiller 20-city home price index rose 6.8 per cent in December compared with the same month a year ago. That's up from a 5.5 per cent annual gain in November.

Nationwide, the report says prices rose 7.3 per cent in 2012. That is similar to other home price measures that show a healthy gain last year.

Prices also rose in December compared with a year ago in 19 of the 20 cities tracked by the index. New York was the only metro area to show a decrease.