Year-over-year home sales dropped 2 percent in May after a record-setting prior month.

In May, a historically busy real estate month, more single-family homes sold—2,767—than last month but failed to top sales trends the same time last year, according to Austin Board of Realtors data released June 19.

ABoR attributes the slight decrease to the record-setting rise in housing costs. Home values typically increase 4 percent annually, according to the Texas A&M University Real Estate Center, but Austin-area home prices increased 9 percent since May 2014, according to ABoR.

Barb Cooper, the 2015 ABoR board president, said in a news release the lack of affordable housing stock is to blame for the slight decrease last month. ABoR estimates that only one-quarter of all homes entering the market priced below $200,000.

“Unfortunately, the majority of single-family homes can no longer be developed within the region in an affordable price range for most homebuyers,” Cooper said in a statement.

The number of active listings increased 6 percent year-over-year to 6,323 properties on the market. That increase is despite a 3 percent decrease in new single-family home listings compared with May 2014.

Overall, the Austin-area housing inventory increased 0.1 months from May 2014 to this year to 2.7 months. The Texas A&M University Real Estate Center recommends a balanced housing market have at least 6.5 months of inventory.