Americans of all ages and income brackets seem to be growing increasingly unhappy at work, a trend that should be a red flag to employers, according to the U.S. Conference Board. A survey done for the board, of 5,000 American households, found only 45 per cent of respondents were satisfied with their jobs, and the under-25 group was the most unhappy. "The downward trend in job satisfaction could spell trouble for the overall engagement of U.S. employees and ultimately employee productivity," said board spokeswoman Lynn Franco. Staff