The U.S. CB leading economic index unexpectedly rose to 0.4% in July, after a 0.4 per cent drop in the month earlier, proving that the world's biggest economy is growing sustainably. Despite positive economic data during last month, the unemployment rate remains above 8% level since February 2009. In the meanwhile, the U.S. economy grew by a tepid 1.5% in the second quarter, after expanding at a 2% rate in the first quarter.