Rising home prices in many housing markets resulted in a modest drop in nationwide housing affordability in the second quarter of 2015, according to the National Association of Home Builders/Wells Fargo Housing Opportunity Index. In all, 63.2 percent of new and existing homes sold between the beginning of April and end of June were affordable to families earning the U.S. median income of $65,800, a drop from the 66.5 percent of homes sold that were affordable to median-income earners in the first quarter, according to a release. The national median home price increased from $210,000 in the first quarter to $230,000 in the second quarter. Meanwhile, average mortgage rates edged slightly lower from 4.03 percent to 3.99 percent in the same period. The median price of a home sold last month in Greater Des Moines was $180,000, up from $175,000 in July 2014, according to the Des Moines Area Association of Realtors. According to the National Association of Home Builders, the rising costs of land and skilled labor are adding to the price of a new home.