TOKYO, Nov. 5 (Kyodo) - The government said Monday its key gauge of the state of the economy remained below the boom-or-bust line of 50% in September for the ninth month in a row. The coincident index, designed to measure the current state of the economy, stood at 12.5% in the reporting month after marking zero in August, the Cabinet Office said in a preliminary report. A reading under 50% is considered a sign of economic contraction and a figure above that is viewed as a sign of expansion. The index of leading economic indicators, a measure of economic growth six to nine months ahead, came to 37.5%, compared with a revised 50.0% in August. The lagging index, which gauges performance in the recent past, was 20.0%, compared with 14.3% in August. The indexes of coincident, leading and lagging indicators compare the current levels of various economic indicators with their levels three months earlier.