Investors are turning increasingly bullish on U.S. markets as they declare its economy in better health than major rivals from Europe to Asia, according to the Bloomberg Global Poll.

As the World Economic Forum's annual meeting began today in Switzerland and Federal Reserve policy makers convene in Washington, 48 percent of respondents predict the U.S. will be among the world's best-performing markets this year, according to the quarterly poll of 1,209 investors, analysts and traders who are Bloomberg subscribers that was conducted Jan. 23-24. That's the highest rating for the U.S. since the poll began in 2009 and it's more than twice that of Brazil and China, the second-ranked markets.

The U.S. economy is improving in the eyes of half those surveyed, compared with 18 percent who are positive about world growth. Investors have yet to embrace tentative gains in fighting Europe's debt crisis, with 48 percent identifying the euro area as one of the worst to invest in and 67 percent predicting that any perceived improvement is temporary and the crisis will deepen again.