America is increasingly diverse, as is its workforce, butcorporate leaders still strongly resemble the cast of “MadMen.”

In 2014, only 5 percent of Fortune 500 CEOs were women. In caseyou forgot, women account for roughly 50 percent of the humanrace.

Whiteness and maleness

But ethnic and racial diversity is also severely lacking in theC-suite, even at companies that have greatly increased thediversity of their overall workforce. In 2014, only 4 percent ofFortune 500 chief executives were racial or ethnic minorities in acountry that is now 38 percent nonwhite.

There are a variety of explanations for the stubborn whitenessand maleness of the C-suite.

For one, the older generation that dominates executive positionsis not nearly as diverse as the nation as a whole.

Similarly, today's executives mostly began their careers whenbarriers based on gender and race were even higher than today.Women accounted for a much smaller share of the overall workforceand were still systematically excluded from many professions.Racial prejudices were also more pronounced. For instance, thepercentage of Americans in support of interracial marriageincreased from 43 percent in 1983 to 87 percent in 2013, accordingto Gallup.

Diversity beneficial for bottom line

But things clearly aren't changing fast enough when it comes tocorporate leadership, companies have determined. Employers haveincreasingly come to the conclusion that diversity in leadership isnot only a good PR move, but beneficial for the bottom line.

A recent study by McKinsey found that companies that were in thetop quartile in terms of gender diversity financially outperformedcompanies in the bottom quartile by 15 percent. The most ethnicallydiverse companies outperformed the least ethnically diverse ones by35 percent.

“More diverse companies, we believe, are better able to win toptalent and improve their customer orientation, employeesatisfaction, and decision making, and all that leads to a virtuouscycle of increasing returns,” McKinsey explained in itsreport.

Similarly, a recent study by PricewaterhouseCoopers found that 85 percent ofCEOs that implemented a designated diversity strategy say theybelieve it had enhanced the company's performance.

Most executives say they have sought to increase diversity bybroadening their recruitment efforts by seeking employees indifferent geographic areas, industries, or demographicsegments.

Related:

Defining 'diversity'

Seeing diversity in action

It's a man's world