Housing prices slipped from prior year levels, largely due to the shift in mix of property types that sold over the quarter. The sharp decline in mortgage rates to record lows resulted in an increase in co-op sales market share, a lower priced property type. Median sales price declined 5.3% to $450,000 from $475,000 in the same period last year. Average sales price slipped 0.8% to $565,291 from $569,799 over the same period. Listing discount, the difference between the list price at the time of contract and the sales price, was 3.5% tighter than 4.8% in the same period last year…