[London] In a quarterly update last week, ZenithOptimedia bumped up slightly its U.S. prediction for 2004 ad spending growth to 5.5% from 5.1% in an earlier forecast in December 2003. But after this year's presidential election and Olympic Games, ZenithOptimedia predicts U.S. ad spending will slide back to 3.9% growth in 2005 and 4.1% in 2006. "It looks like fairly average growth," said Jonathan Barnard, ZenithOptimedia's knowledge management manager. "We're not talking about a surge after the large decline [in ad-spending growth] between 2001 and 2003, unfortunately." The company also cut earlier estimates of 3% growth for 2003, saying U.S. ad spending last year grew less than expected, by just 1.9%. The quarterly update covered the eight ad markets in Europe, North America and Japan that account for 75% of worldwide ad spending. The eight are forecast to grow 4.2% in 2004, and 3.4% next year, ZenithOptimedia said. The brightest spot is Japan, the world's second biggest ad market. After growth of just 0.8% last year, ZenithOptimedia forecasts 1.5% growth this year and 2% next year.