BY LILY LEUNG, UNION-TRIBUNE FRIDAY, JANUARY 7, 2011 AT 12:19 P.M. More Americans are renting, a sign of continuing economic distress that’s also seen in San Diego County. Nationwide, the rate of apartment vacancies dipped to 6.6 percent in the fourth quarter from 8 percent during the same time one year ago, marking a two-year low, [...]