Prudential Douglas Elliman Real Estate is out with two mega-reports today; one looking at Manhattan real estate trends over the past decade and another looking specifically at the market for townhouses in the same time period.

According to the townhouse report, the average cost of a Manhattan townhouse has increased 116.3 percent between 2002 and 2011, from $2.29 million to $4.96 million.

However, the average townhouse sale price slipped more than 9 percent from the previous year, when it was $5.47 million, the report said. 240 townhouses changed hands in 2011, up from 197 the previous year.

Luxury townhouses (those in the top 10 percent of the market), sat on the market for an average of 388 days in 2011, a sharp increase from 2010, when the average DOM for the luxury segment was 129 days.

The overall Manhattan co-op/condo market held stable, with more than 10,000 sales in 2011, the third-highest in the decade, according to Prudential Douglas Elliman.

The median sales price was $850,000 in 2011, down 3.4 percent from $880,000 in 2010, and up 88.9 percent from $450,000 in 2002.