The service industry expanded last month, surprising economists who had predicted the industry would contract slightly, Bloomberg reported.

The Institute for Supply Management’s index of nonmanufacturing businesses, which encompasses about 90 percent of the economy, rose to 52 from 49.6 in March. A reading greater than 50 signifies growth. Economists surveyed by Bloomberg had predicted an index reading of 49.1.

The service industry had contracted during January, February and March. The last time the index reading was less than 50 for three consecutive months was in 2001 and 2002 as the economy was emerging from a recession. April’s reading could be a strong sign that the economy will weather the housing slump and credit crisis.