The Michigan Business Activity Index, compiled by Comerica Bank, gained 6 points in May to close at 114, compared with 108 in April, according to statistics released today. A year earlier the index stood at 115. Year-to-date, Michigan's economy is running 1.3 percent behind the first 5 months of 2002. "In May, steel output and motor vehicle production gained sharply, while most other index components, including employment, were stable," according to David L. Littmann, chief economist with Comerica Bank.The Michigan Business Activity Index (MBAI) represents ten different measures of Michigan economic activity compiled monthly by the Economics Department of Comerica Bank. The MBAI is seasonally adjusted, corrected for inflation, and expressed on an index basis with base year 1996 equals 100. The MBAI series has been calculated monthly since 1957 and depicts state economic activity over seven full swings of the U.S. business cycle.