Belgium: 50%
U.K.: 50%
Germany: 45%
France: 41%
U.S.: 35%
Note: U.K. rate will be cut to 45% next year. Source OECD
France's Hollande Outlines Austerity Goals WSJ 9 September 2012
Doesn’t tell the full story though. Often countries with high marginal rates have so many different deductions your head would spin.
Which of those socialist countries taxes worldwide income?
Which of those socialist countries has an exit tax on wealth?