DETROIT In yet another sign that the Michigan economy is strengthening, Comerica reported Tuesday its Detroit Area Business Activity Index jumped 21.6 percent from a year ago, with real growth 12.9 percent above the first quarter of 2003.

The Index registered 114 points in March, compared to a year earlier index reading of 94 points.

“Regional strength is returning gradually, but appears especially robust when compared with pre-war 2003,” said David Littmann, chief economist with Comerica Bank. “A similar distortion will occur in second quarter comparisons for our economic region, but will not mask the real growth and return to profitability that is occurring.”

Comerica Bank compiles the Detroit Area Business Activity Index (DABAI) monthly from eight different measures of regional activity which are seasonally adjusted, corrected for inflation, and expressed as an index with 1996 as base year equal to 100. The Economics Department of Comerica Bank has calculated the DABAI monthly since 1957, depicting Metro-Detroit’s economy over seven full swings of the U.S. business cycle.