WASHINGTON (Reuters) - The number of Americans filing new claims for unemployment benefits fell sharply last week to the lowest level in more than four and a half years, according government data on Thursday that suggested improvement in the labor market. Initial claims for state unemployment benefits fell 30,000 to a seasonally adjusted 339,000, the Labor Department said. It was the lowest number of new claims since February 2008. The prior week's figure was revised up to show 2,000 more applications than previously reported. ...