The monthly Rural Mainstreet Index fell to it lowest level in almost two years for in August -- a factor of plummeting crop prices, said Ernie Goss, an economist at Creighton University and creator of the index. Based on a survey of rural bank CEOs in a 10-state region, the regional index fell to 48.3 from July's 51.8. Although rural businesses continue to hire at a solid pace, a confidence index, which reflects expectations for the economy six months out, plunged to 39.9 from last month's 42.9, largely based on weaker commodity prices. Iowa's August index was slightly higher than the region at 50.6.