Assessed property values in Los Angeles County have jumped 11 percent over the last year to a record $950 billion, led by sales of single-family homes, County Assessor Rick Auerbach reported Tuesday.

“We’re a long way from the two-to-three percent value gains of the 1990s and are approaching a trillion-dollar (assessment) roll next year, even with the likelihood of a continuing slowdown in the real estate market,” Auerbach said.

Sales of properties requiring reassessment under Proposition 13 mostly single-family homes added $65 billion in assessed property values to the county roll, one of the largest gains ever. Each property that changed ownership resulted in an average increase of $332,000 in assessed value, compared to $262,000 last year.

Auerbach said low interest rates and a short supply of low- to medium-priced housing were key factors driving the demand for single-family homes.

Another factor was the automatic two percent increase in assessed value for all properties that did not change ownership; that added $16 billion to the roll. New construction added $7 billion to the assessment roll, up from $6 billion last year.

Auerbach said that the slowdown in the housing market has shown up in the number of changes of ownership recorded at his office this year: 504,300 changes in ownership compared with 521,700 in 2005. Construction permits were virtually flat at around $109,000.

The growth in assessed values over the last 12 months was greatest in the Antelope Valley cities of Lancaster and Palmdale, with increases of 29 percent and 21 percent, respectively.

Just a few years ago, homes in these bedroom High Desert communities were selling at a fraction of homes in the L.A. basin. Now they are closing the gap, thanks to droves of people seeking refuge from stratospheric home prices in the rest of the county and a healthy dose of commercial and industrial construction.

Other communities posting major gains in assessed values over the last 12 months included Azusa (18 percent), Signal Hill (15 percent), and Malibu and West Hollywood (both at 14 percent).

In his report, Auerbach cited the sale of a 550-acre former nursery site in Azusa for future residential development as the key factor for that community’s huge gain. The increases in Signal Hill and Malibu were largely driven by the desirability of land in those cities, while West Hollywood’s gain was attributed to an acute shortage of housing.

The city of Los Angeles remained the highest valued municipality, with a total assessed value of $349 billion, up 10.9 percent from 2005. Long Beach was second at $39 billion, up 12.6 percent from 2005.

For the first time in several years, no city in L.A. County posted a drop in assessed value; the smallest gain of 2.8 percent was recorded in Carson.