The median price for all residential properties sold in May rose nearly 19 percent from a year ago to $380,000, the highest price since May 2008, when the median value also was $380,000.

A 19 percent year-over-year home-price increase for a May is uncharacteristic, DataQuick numbers show. The previous high, which was 20 percent, was recorded in March 2004, just before the peak of the real estate market.

Sales also saw a significant jump in May. They rose 16 percent from a year ago to 3,762, the best recording for a May since 2006, when roughly 4,300 properties were sold. “Price measures continue to rise for two simple reasons,” DataQuick President John Walsh said in a recent report. “First, demand for homes has risen at a time when the available supply is unusually low. Prices have had nowhere to go but up in many areas. “Second, the gains are especially high right now because of the change in market mix,” Walsh said. “Sales of lower-cost homes have fallen at the same time activity in the higher price ranges has risen.”

Inventory has posed a challenge to potential homebuyers for at least a year. There were about 4,200 active listings in San Diego County last month, about half of what was available to buyers the same time a year ago, based on figures from the Greater San Diego Association of Realtors. Listings hit their highest point at 13,123 in September 2010, when foreclosures peaked in San Diego County, according to the group’s numbers, which start in summer 2009.

Limited inventory has pushed buyers to go to greater lengths to increase their chances of snagging a property and stand out from competitors. Increasingly popular tactics include submitting cover letters with photos and personal stories with their purchase offers, said Linda Lee, president of the local Realtors group. “I think demand is extremely high because interest rates remain low and any inventory coming onto the market gets grabbed quickly,” Lee said.

The 30-year fixed mortgage rate is at 3.43 percent, near the all-time record low of 3.31 percent set in late November, according to mortgage-finance company Freddie Mac. Those numbers date back to 1971. The tightened housing supply is in large part due to a high percentage of homeowners who are underwater on their mortgages and cannot sell their homes, a consequence of the housing crash. Although home prices are consistently rising, they’re still about off 26 percent from the peak median price of $517,500 recorded in fall 2005.

The share of San Diego County homeowners who owe more on their properties than they’re worth has seen some improvement. The percentage fell from 31 percent in the third quarter to 28 percent in the fourth quarter, based on figures from Zillow.

Note: The most current and accurate listing information always comes from the MLS, and more often information on Zillow, Trulia, RedFin and Realtor.com is outdated or erroneous. As a Realtor with access to the San Diego MLS, I’m happy to provide current MLS information to you at any time!