WASHINGTON (AP) — The number of available jobs posted by U.S. employers rose in December to the highest level in 14 years, a sign recent strong job gains will likely continue. Employers also filled more jobs and more employees quit, two additional signs of an improving labor market. More quits are a sign of confidence in the labor market, because people typically quit when they have another job lined up, usually at higher pay, or are optimistic that they can find a new position. The figures echo last week's monthly employment report, which showed that businesses are adding jobs at a robust pace and even paying more to attract workers.