An index that points to future construction activity dropped in April for the second time this year after recording gains in 13 of the last 15 months, the American Institute of Architects (AIA) said today. The April score for billing activity was 48.8, down from 51.7 in March. Any score above 50 indicates an increase in billing activity. However, separate measures of inquiries for new projects advanced above 60, suggesting that that demand for design services remains strong, Jessica Reinert, executive director of AIA Iowa, said in a release.