Boston homes experienced year-over-year gains of 15.7% in May, but lagged far behind the national average, according to the S&P Corelogic Case-Shiller Index.

The annual home-price gain across the nation stood at 19.7% in May, down 1.1 percentage point from the previous month, showing a minor slowdown in spite of continued strength in the market.

The 10-City Composite was up 19% from a year ago, but dipped from 19.6% a month earlier. The 20-City Composite was up 20.5% in May year over year, also down slightly from 21.2% in April.

The top three cities with price gains were Tampa (36.1%), Miami (34%) and Dallas (30.8%).

“Housing data for May 2022 continued strong, as price gains decelerated slightly from very high levels,” Craig J. Lazzara, managing director at S&P DJI, said in a press release. “Despite this deceleration, growth rates are still extremely robust, with all three composites at or above the 98th percentile historically.”

Lazzara said the strong price growth might drop further due to rising interest rates making it more expensive to finance a mortgage.

CoreLogic Deputy Chief Economist Selma Hepp said in a press release that signs of slowing homebuyer demand are spreading, and that the report reveals a second month of slowing growth.

“Nevertheless, some markets continue to heat up, particularly in Florida, but also Chicago, Boston and New York – marking search for deals in regions that suffered outmigration during the pandemic,” she said. “Bifurcation in housing markets is also reflected in the ongoing competition for attractive properties that continue to have multiple offers and sell over the asking price, compared to those that are now seeing price reductions and remain unsold. But, given the continued pressure on properties that sell, home price growth is forecasted to remain elevated and in the mid-teens through the end of the year.”