Single-family sales of existing homes rose five percent to a seasonally adjusted annual rate of 4.60 million in May from 4.38 million in April, and are 12.7 percent higher than the 4.08 million-unit pace in May 2012. The median existing single-family home price was $208,700 in May, up 15.8 percent above a year ago, the strongest increase since October 2005 when it jumped 16.9 percent from a year earlier.

Existing-home sales improved in May to the highest rate since November 2009, while the median price continued to rise by double-digit rates from a year earlier, according to the National Association of Realtors.

Total existing-home sales, which include single-family homes, townhomes, condominiums and co-ops, rose 4.2 percent to a seasonally adjusted annual rate of 5.18 million in May. The pace increased from 4.97 million in April, and is 12.9 percent above the 4.59 million-unit pace in May 2012. Sales have stayed above year-ago levels for 23 consecutive months.

"The housing numbers are overwhelmingly positive. However, the number of available homes is unlikely to grow, despite a nice gain in May, unless new home construction ramps up quickly," said Lawrence Yun, NAR's chief economist. "The home price growth is too fast, and only additional supply from new homebuilding can moderate future price growth."

The national median existing-home price for all housing types was $208,000 in May, up 15.4 percent from May 2012. This marks 15 consecutive months of year-over-year increases, and six straight months of double-digit increases. The monthly increase was the strongest price gain since October 2005, which jumped a record 16.6 percent from a year earlier. The last time there were 15 consecutive months of year-over-year price increases was from March 2005 to May 2006.

Total housing inventory at the end of May rose 3.3 percent to 2.22 million existing homes available for sale, which represents a 5.1-month supply at the current sales pace, down from 5.2 months in April. Listed inventory is 10.1 percent below a year ago, when there was a 6.5-month supply.

The median time on market for all homes was 41 days in May, down from 46 days in April, and is 43 percent faster than the 72 days on market in May 2012. Short sales were on the market for a median of 79 days, while foreclosures typically sold in 43 days and non-distressed homes took 39 days.