WASHINGTON (AP) — U.S. home prices rose in January at the fastest pace since the summer of 2006, just before the housing bubble burst. The gain shows the housing recovery is strengthening ahead of the spring buying season.

The Standard & Poor's/Case-Shiller 20-city home price index climbed 8.1 percent in the 12 months ending in January That's up from a 6.8 annual gain in December. Prices rose in all 20 cities, led by a 23 percent gain in Phoenix.

Prices rose in 11 of 20 cities on a month-over-month basis. Those numbers are not seasonally adjusted and reflect the slower winter buying period.