Billings to architecture firms slowed in June but remained positive for the ninth consecutive month, the American Institute of Architects said. The organization’s billings index, which is an indicator of future construction activity, was 51.3 last month, down from 52.8 in May. Any score above 50 is a sign of growth. “Iowa firms continue to see a demand for their services this summer,” said AIA Iowa Executive Director Jessica Reinert. “However, the regional average of the Midwest business conditions seems to be flat so it is something our architects are keeping an eye on.” The Midwest index measured 49.8.