LYNN – Single-family home sales gained momentum in Lynn over the past year, some of the activity spurred by declining real estate prices.According to The Warren Group, which tracks real estate sales across the state, 167 single-family homes were sold in Lynn in May 2009 compared to 133 in May 2008. The difference represents a net increase of 34 in the number of single-family home sales.However, the median single-family home sale price in Lynn declined from $216,000 in May 2008 to $179,000 in May 2009 – a drop of 17 percent.Vincent Valvo, editor-in-chief of The Warren Group, said each community’s real estate market is different and a variety of reasons can be cited as the cause for change in the number of sales. “If real estate prices go down, that might be why you see more sales. There could be a whole bunch of foreclosures in the same community, or on the other hand, you might have a housing development and they sold out all at once, or a condo development that finished up,” he said.Valvo ackno-wledged the Lynn data from May to May represents a pretty big jump.Although the firm’s database did not indicate whether the Lynn sales were the result of bank foreclosures, Valvo said banks do not want to be landlords. “The banks don’t want to hold onto these properties so they sell them at deep discount,” he said. “You also have a lot of first-time homebuyers entering the market, so that will account for some of the less-expensive home sales.”Speaking generically, Valvo noted that most communities experienced a decrease in single-family home sales. “In that sense, Lynn is lucky that the numbers went up,” he said.The single-family three-bedroom home at 27 Collins St. was among those sold during May 2009. The price: $65,000. The home previously sold for $239,000.Another Lynn home at 19 South St. sold during the same period for $25,000. The previous owner paid $111,572.Lynn home sales were clearly an anomaly, given that home sales in Massachusetts dropped 13 percent in May, according to The Warren Group. It was the lowest level for the month in nearly two decades.The Boston-based Warren Group also reported Tuesday that single-family home sales fell 13.1 percent, compared with last May. There were 3,256 home sales, the lowest since 3,238 sales in May 1990.Further, the median selling price dropped 13 percent to $280,000 from $322,000 in May 2008The Massachusetts Association of Realtors reported Tuesday that home sales fell 15.3 percent from last May. The Realtors group said the median selling price fell to $284,000, a decrease of 11.8 percent compared with $322,000 last May.The organizations use slightly different methods of calculation.