Since last fall, price indicators for the Queens housing market have been rising. An improving local economy, low mortgage rates, and low inventory have played a role in the increases. Median sales price jumped 20.7% to $446,434 from the same period last year and the ninth increase of the past 11 quarters. Average sales price followed the same pattern, rising 14.6% to $492,340 over the same period. Low inventory has been a key reason sales had declined from the prior year quarter. There were 4,695 listings in the first quarter, down 16.4% from the prior year quarter…