The Bay Area's nine-county region saw a total of 7,494 new and resale houses and condos change hands in December 2011, up 4.4 percent from the same month in 2010, said DataQuick, a San Diego real estate information service. It was the sixth month in a row that sales volume rose compared with the prior year.Absentee buyers, mainly investors, were out in record numbers, DataQuick said. They accounted for almost a quarter (23.8 percent) of all the homes sold and paid a median of $225,000 in December. All-cash buyers, again largely investors, accounted for 27.4 percent of sales.The median price paid was $351,000, a 3.5 percent slump from December 2010. It was the 15th consecutive month of a decline in the median, although it is still above the recent low of $290,000 reached in March 2009. The all-time-high median sales price for the Bay Area was $665,000 in June and July 2007.