TAMPA - Tampa Bay's fall in home sales prices during the past year is among the nation's steepest, but the rate of decline is slowing.

Nationally, home prices in May fell by the steepest rate ever.

Sales prices in the Tampa area fell 20.2 percent in May from a year ago, but the drop was slightly smaller than the 20.4 percent decline in April, according to Standard & Poor's Case-Shiller home price index.

The month-to-month decline, however, has slowed considerably. From April to May, prices fell 0.8 percent, narrowing from the 2.1 percent drop from March to April.

Real estate professionals hope it points to the beginning of a bottom in Tampa Bay's housing market downturn, but David Blitzer, chairman of the index committee, said it's too early to cheer.

"I wouldn't dash to be optimistic at any of this," Blitzer said. "I wouldn't want someone to say, 'Fantastic, the bottom is here.' Getting to the bottom takes working down excess supply and increasing demand. That is not really taking shape yet."

Tampa was among seven metro areas that represent a possible bright spot in the otherwise dismal report. Boston, Detroit, Minneapolis, New York, Dallas and Atlanta all showed smaller annual declines.

Boston had monthly gains in prices for two straight months, Blitzer said, a sign that its market is nearing a bottom. What's happening in Boston should give hope to people in Tampa, he said. But since Boston's rise in home prices peaked months before Tampa's did, the Bay area is likely in for a long wait before hitting bottom, he said.

Also, Boston's prices didn't shoot up as much as Tampa's, so they didn't have as far to fall, Blitzer said. The annual price decrease in Boston in May was 6.2 percent.

The nation's record price drop is based on an index that includes 20 metro areas. The index fell 15.8 percent in May when compared with last year, the steepest decline since its inception in 2000.

The organization's 10-city index, also released Tuesday, plunged 16.9 percent, its biggest decline in its 21-year history.

No city in the Case-Shiller 20-city index had price gains in May, the second straight month that's happened. The monthly indices have not recorded an overall home price increase in any month since August 2006.

Nine metropolitan cities - Las Vegas, Miami, Phoenix, Los Angeles, San Diego, San Francisco, Seattle, Portland, Ore., and Washington - posted record declines in May. And the value of housing in Detroit is now lower than it was in 2000.

Las Vegas recorded the worst drop, with prices plunging 28.4 percent in the month. Miami came in a close second, with prices down 28.3 percent.

Charlotte, N.C., posted the smallest drop at 0.2 percent. Until April, the North Carolina city had been the last metro still showing price gains.

Information from The Associated Press was used in this report. Reporter Shannon Behnken can be reached at               (813) 259-7804        or sbehnken@tampatrib.com.