SOUTH PORTLAND – Sales of existing single-family homes in Maine decreased 18.5 percent in May from the same period in 2006, according to data from the Maine Association of Realtors. The median sales price of Maine homes also dipped about 2 percent, to $193,000, the data indicated.

When statistics from March, April and May are combined and compared to the same period last year, the statewide median sales price rose 1.5 percent, to $195,000, but sales were down 14.8 percent.

Linda Gifford, spokeswoman for the Maine Association of Realtors, said the decline in existing home sales is part of an 18-month downturn that was anticipated by experts.

“It happens, but we don’t expect it to last too long,” Gifford said in a recent telephone interview.

While Maine’s negative numbers mirror the national market, Gifford said, the state has been spared the widespread foreclosure rates that have recently destroyed entire neighborhoods nationally.

“We did not think predatory lending was happening too much in Maine, and really we haven’t seen a lot of foreclosures like the rest of the nation,” said Gifford.

The data for the March, April and May quarter revealed that Lincoln County bucked the statewide trend. A little more than 17 percent more houses were sold in 2007 than during the same period in 2006. The median sales price increased almost 15 percent, from $208,000 in 2006 to $239,100 in 2007.

In Penobscot County, 26.6 percent fewer houses were sold in the 2007 quarter than during the same period in 2006. But the median sales price increased 4.6 percent to $146,500.

In Washington County, the same number of houses were sold for the quarter, but the median sales price fell 20 percent from $113,750 in 2006 to $90,990 in 2007.