U.S. economic statistics are the best in the world, economists contend, but they are imperfect because they have not evolved as quickly as the economy. "We still spend too much [money] collecting manufacturing and agricultural data, the old backbone of the economy," said William C. Dunkelberg, professor of economics at Temple. For example, the industry-classification system government agencies use to collect data includes 10,538 categories for manufacturing, 53 percent of the total. However, manufacturing accounted for just 11 percent of gross domestic product and 9 percent of total employment.