By John S. McClenahen The Conference Board's index of leading economic indicators rose 0.5% in May, far stronger than April's 0.1% increase but below March's 0.8% increase. The index now stands at 116.5 (1996=100). "May's 0.5% increase keeps the current growth rate of the leading index in the 3.5% to 4.5% [annual rate] range," the New York-based business research group said when it released the latest data on June 17. Eight of the 10 indicators that make up the index posted increases in May, including average weekly manufacturing hours, manufacturers' new orders for consumer goods and materials, and manufacturers' new orders for nondefense capital goods. Only consumer expectations and stock prices were negative.