London (CNN Business) Global inequality is "out of control" because of biased economic systems that exclude many women while allowing billionaires to amass huge fortunes that do little for society, according to Oxfam International.

The charity is calling on governments to implement policies that ease the burden on women who provide care for children and the elderly, often for little or no pay. Oxfam suggests higher taxes on the wealthy, and more spending by national governments on child- and health care.

Oxfam's annual report on inequality was released ahead of the World Economic Forum in Davos , Switzerland, which each year brings together many of the world's wealthiest and most influential people. Among the report's key findings:

The world's 2,153 billionaires have more wealth than 4.6 billion people.

The 22 richest men have more wealth than all the women in Africa. According to the UN, there are 326 million aged 20 and over.

The world's richest 1% have more than twice as much wealth as 6.9 billion people.

The value of unpaid care work by women aged 15 and over is $10.8 trillion annually.

The number of billionaires has doubled over the past decade.

The 63-page report argues that world leaders are not doing enough to address the widening gap between the poor and the rich. It focuses this year on policies that allow men to dominate the top ranks of business and government. Economic inequality, the report argues, is built on gender inequality.

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