(CNN Business) The world's billionaires are growing $2.5 billion richer every day, while the poorest half of the global population is seeing its net worth dwindle.

Billionaires, who now number a record 2,208, have more wealth than ever before, according to an Oxfam International report published Monday. Since the global financial crisis a decade ago, the number of billionaires has nearly doubled.

The annual study was released ahead of the yearly World Economic Forum in Davos, Switzerland, which brings together some of the wealthiest and most influential people on Earth. The 106-page report is meant to call attention to the growing gap between rich and poor.

The combined fortunes of the world's 26 richest individuals reached $1.4 trillion last year — the same amount as the total wealth of the 3.8 billion poorest people.

Most of these mega-wealthy are American, according to the Forbes list of billionaires used by Oxfam. The names include Amazon's Jeff Bezos , Microsoft's Bill Gates, Berkshire Hathaway's Warren Buffett and Facebook's Mark Zuckerberg, who collectively are worth $357 billion, according to Forbes.