House sales increased 6.1 percent to 2,851 in April compared with April 2012, the Iowa Association of Realtors (IAR) said today. The association's monthly report showed improvements in all measures of the real estate market. Average sale price was $146,885 in April, up from $144,813 a year ago. Houses were on the market an average of 99 days, compared with 111 days the same time last year, and the inventory of houses for sale dropped to 18,331 from 21,061, the IAR said.