Louisville home sales over the past year are down from the previous 12 month period.The Greater Louisville Association of Realtors announced that June home and condo sales have dropped by 23 percent when compared to June 2010, while the median home price stayed around $140,000.This is partly due to a tax credit that Congress awarded last year to homebuyers, but that can make it hard to predict the affects the tax credit had on the market, said Brent Shaw, a Realtor with Rick Shaw Realtors and member of the Greater Louisville Association of Realtors.“That was a boost doing the tax credit program. Whether it was a short term boost or not it’s going to be hard to tell. It’s probably going to take a couple years to really see what it did to the overall market,” said Shaw.Members from the Greater Louisville Association of Realtors have sold more houses in June than any month this year, but the number of home sales in the summer is always highest, said Shaw.