Delores Conway, director of the USC Lusk Center's Casden Real Estate Economics Forecast, predicted recently that apartment rents will rise by 4 percent to 5 percent this year, based on a separate survey using different figures. That compares to a 5.3 percent rise in 2006 and 6.5 percent in 2005, according to Conway's figures. Still, rents will continue going up, she said, because the demand for housing outstrips the supply of available apartments. The recent shake-up in the subprime lending industry means that some potential homebuyers also will have a harder time borrowing money and will have to continue renting. "We're still going to see significant rent growth," Conway said. "Occupancy is very high. And also, we've had a lot of conversions of apartments to condos." Just 5 percent of all 122,000 units in RealFacts' survey were vacant this past winter, RealFacts reported. The vacancy rate was up just 0.4 percent from a year ago, an insignificant change, Conway said. In all of Southern California, the average apartment rent this past winter was $1,439 a month, up 6 percent from the previous year, RealFacts reported. The region's vacancy rate was 5.5 percent. The average rent in Northern California was $1,270 a month, with a vacancy rate of 5.3 percent.