Radar Logic, a real estate data an analytics company based out of New York, reported Monday through their Residential Property Index (RPX) that the sale price for a apartment, as of May 31, in Manhattan increased 6.7% to $1,017.49 per sq. ft. year-over-year. This is price remained steady from April 2010 to May 2010. The increase in sale price acted as an indicator of increased demand between May 2009 and May 2010 as sales almost doubled. May 2009 marked the lowest sales activity in the Manhattan condo market; now averages sales are only 4% below the 10-year average. The majority of sales were derived by existing unit sales, up 72% since last year. New-unit sales increased considerably in their own right, rising 188% relative to the prior year, to 21% of total sales, up from 15%. Foreclosed and REO condo sales remain rare in Manhattan, accounting for just over 2% of May 2010's total sales. RPX research indicated that, although there's word of a rebound for the Manhattan housing industry, landlords reported a decrease in rent prices, possibly attributable to a new strategy by young renters called "doubling up." This means that renters will share apartments rather than live on their own. But even renters are sharing space, according to the RPX, they prefer comfort to price. The median size of condos sold in Manhattan increased 15% to 951 sq. ft, up from 825 sq. ft. Median new-unit size sales jumped 77% in May 2010 compared to May 2009, to 1,356 sq. ft. from 765.5 sq. ft. All eight Manhattan districts tracked by Radar Logic posted year-over-year gains in sales activity, the largest difference being in the Financial District, sales grew by 550%. However, sale prices grew in only six districts (see figure). Write to Christine Ricciardi.