The hourly-wage pay gap between women and men has narrowed but also stubbornly persisted over the past 30 years, a study released this month by the Pew Research Center found.

In 1980, women earned an average 64 cents for every dollar men earned, a pay gap of 36 cents. Since then, the pay gap has narrowed to 16 cents. Women earned 84 cents for every dollar men earned in 2012.

But younger women have earned more than their sex’s average each year. In 2012, women ages 25-34 earned 93 cents for every dollar men earned.

Pew suggests several factors are driving up women’s wages. Women are more educated and more active in the workforce than in the past, many women have moved into previously male-dominated occupations, and men’s earnings have fallen. Workplace discrimination has also fallen.

Today, the gap is narrowing at a slower pace. Women narrowed the gap by 11 cents in the 1980s, by three cents in the nineties and by six cents in the 2000’s. So women beginning their careers from 1990 to 2000 on average saw the wage gap widen slightly as they aged.

One reason is that women are likely to accept lower pay in return for non-monetary benefits once they have children.  Since women are still mainly responsible for child care, many women take a significant amount of time off from work (39 percent), reduce their working hours (42 percent), or quit work to care for their children (27 percent).

Women are also more likely to work in lower-paid occupations, like office or administrative support jobs, which pay about $15 per hour, compared to engineering jobs, mainly held by males, which pay about $30 per hour.

And though discrimination has lessened, women are still more likely than men to say they have experienced gender discrimination in the workplace.