Despite a 23 percent decline in sales volume, home prices in Brooklyn continued to increase last year, according to a study by appraisal firm HMS Associates. The average sales price for homes rose to $634,915, a 4 percent increase from 2006. The pace of growth in sales prices was under half the rate of 2006. Prices for single-family homes rose 10.2 percent to $669,000 and multi-family home prices went up 18.6 percent to $1.4 million. Co-op prices increased 8.8 percent to $444,000 and condo prices increased 7.5 percent to $587,000.