OMAHA, Neb. (AP) — A monthly survey of business supply managers suggests a slight decline in the economic conditions for nine Midwest and Plains states, according to a report released Thursday.

The Mid-America Business Conditions Index report said the overall regional economic index dropped to 55.5 in May from 61.4 in April. The March figure was 60.1.

Results are compiled into a collection of indexes ranging from zero to 100. Organizers say scores above 50 suggest growth in that factor, while scores below suggest decline.

“The overall index over the past several months indicates a healthy regional manufacturing economy, and points to healthy growth for both manufacturing and nonmanufacturing through the third quarter of this year,” said Creighton University economist Ernie Goss.