US presidential candidate Mitt Romney paid 13.9% tax on his multi-million dollar income - promoting a debate about tax levels among the "super rich".

Meanwhile, protesters in the Occupy Wall Street movement claim they speak for the "99%" of Americans who stand in opposition to the one per cent who control the majority of the country's wealth.

But how accurate are these figures?

While developed countries have grown richer over the past 30 years, not everyone's pay packets are getting bigger at the same rate. Income inequality is on the rise in most developed countries, according to the Organisation for Economic Co-operation and Development (OECD).

In the United States, the 400 richest individuals earn roughly the same as the bottom 50% of the population.

About one third of the world's 100 richest people live in the US.

Who are these billionaires? Where do they get their wealth from? And are the super-rich being super-taxed?