Rising public debt and elections in Europe and the US have once again raised the debate over taxes.

Europe's debt crisis is forcing some countries to raise taxes. Spain, for example, raised its personal tax rate by 2 percentage points to 45% last year and Frances newly elected Socialist Party is also proposing hiking taxes on the rich.

In the US, President Barack Obama has proposed the Buffett rule, aimed at ensuring households that earn more than USD 1 million a year pay more in taxes proportionally than middle-class families. Republicans have opposed the tax, calling it a "gimmick" and arguing it will hurt growth.

But there are many countries with top tax rates higher than the US's 35%. In fact, the US is ranked 23rd in terms of the top marginal tax rate among 96 countries surveyed by KPMG in 2011.