The global economy is growing faster than expected only a few months ago thanks to resilient U.S. activity while inflation is converging more quickly than expected with central banks' targets, the OECD said on Thursday, upgrading its outlook. The global economy would maintain the 3.1% growth rate seen last year and pick up marginally to 3.2% next year, the Organisation for Economic Cooperation and Development said, upgrading forecasts dating from February for growth of 2.9% this year and 3% in 2025.