Concerns about the U.S. economy and job market increased in September, driving a key index of consumer confidence to its lowest level in almost two years, a private research organization reported Tuesday. The Conference Board said its consumer confidence index fell to 99.8, a nearly 6-point drop from the 105.6 recorded in August. The figure was far below analysts' expectations and marked the lowest level since 98.3 in November 2005, when gasoline and oil prices soared after Hurricanes Katrina and Rita hit the Gulf Coast. “Weaker business conditions combined with a less favorable job market continue to cast a cloud over consumers and heighten their sense of uncertainty and concern,” said Conference Board research director Lynn Franco. “Looking ahead, little economic improvement is expected, and with the holiday season around the corner, this is not welcome news.” The present situation index, which measures how consumers feel about the current economy, fell to 121.7 from 130.1 in August. The expectations index, which measures consumer attitudes over the next six months, declined to 85.2 in September from 89.2 the previous month. Economists closely watch consumer confidence indexes for clues on consumer spending, which accounts for two-thirds of total U.S. economic activity.