OMAHA, Neb. — Figures have dropped for a fifth straight month in a survey of supply managers in nine Midwest and Plains states, providing evidence of a regional economic slowdown.

A report issued Monday said the overall Mid-American Business Conditions Index dropped to 39.6 in December from 40.7 in November, 41.9 in October, 47.7 in September and 49.6 in August.

Creighton University economist Ernie Goss oversees the survey, and he again blamed manufacturing losses linked to the strong dollar and economic weakness among trading partners.

The survey results are compiled into a collection of indexes ranging from zero to 100. Survey organizers said any score above 50 suggests economic growth. A score below that suggests decline.

The survey covers Arkansas, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, Oklahoma and South Dakota.