Business at Midwest architecture firms is in flux on the plus side of an index compiled by the American Institute of Architects. The association's billings index for September reached 54.3, its second-highest reading of the year. In the Midwest, architects ranked their activity at 51, down from 52.8 last month. Any reading above 50 represents an increase in billings, which generally precede construction activity by nine months to a year. Inquiries about new projects dropped to 58.6 from 63 in August. Business is "fluctuating" in the region, but architects are "integrating new technologies ... and increasing their productivity levels to make the most of their resources," Jessica Reinert, executive director of the Iowa chapter of the American Institute of Architects, said in a news release.