The number of house sales and pending sales dropped in September from August in Greater Des Moines, but year-to-date numbers show that closed deals have increased, outpacing 2011 numbers by 1,055, the Des Moines Area Association of Realtors said. The association’s report shows that 722 contracts were written in September, which was down from 897 in September 2011. There were 4,371 active listings, which is down from the same period last year by more than 1,000 listings. Average sale price increased to $177,394 last month from $172,839 in August and $170,682 in September 2011. “We’re selling more homes along the entire spectrum of the market,” Ken Clark, president of the real estate group, said in a release. He pointed out that 16 houses sold last month at prices exceeding $500,000.