The past year was hardly kind to investors, yet billionaires as a group—that is, those with a net worth of $1 billion or more—managed to make the volatile market conditions in 2015 work in their favor.

In total, the wealth of the world’s billionaires grew by 5.4% to $7.7 trillion, while the number of billionaires also grew by 6.4% to 2,473, according to a billionaire census by Wealth-X, a firm that tracks the ultra-wealthy.

That growing number of billionaires was largely boosted by baby boomers passing their wealth on to their heirs. Billionaires who inherited or partially inherited their net worth grew 29.9% year-on-year—the fastest growing segment of all billionaires.

But the large majority of billionaires still require some form of entrepreneurialism to maintain their status. Some 56% of billionaires in 2015 were self-made and 87% made at least some of their fortunes themselves.

Billionaires have grown more cautious about the markets however, with cash accounting for 22.2% of their net worth, up from 19.1% last year and the highest percentage since Wealth-X began tracking the data in 2010. In response to uncertain market conditions such as the crash of the Shanghai Composite in the summer of 2015, it seems likely that billionaires began taking their money off the table.

That said, billionaires control slightly less of the world’s wealth than they did two years ago. While billionaires held about 4% of global wealth in 2014, they held 3.9% in 2015, suggesting that other economic classes grew their wealth at a slightly faster pace than billionaires.

Despite efforts to include more women in the startup space and at the executive table, male billionaire over-representation still increased, according to the report. About 8.4 male billionaires exist for every female billionaire today, up from a 8.1:1 ratio a year ago.