The gender wage gap is widening, particularly for women under 40, according to a study by HR analytics and software company Visier.

In 2017 the gender pay gap for workers under age 40 increased when compared to 2016. In 2015 women under age 40 earned on average 81 cents for each dollar earned by men. In 2016 this wage gap improved slightly to 82 cents. However, in 2017 this gender wage gap for younger women increased, with women under age 40 earning an average of 79 cents for each dollar earned by men. At the same time, the gender wage gap for workers over age 40 did not experience any meaningful improvement.

In addition, says the study, when comparing the performance ratings of men and women in 2015, 2016, and 2017, women are increasingly achieving top performer status more frequently than men. In 2017 women were 21 percent more likely to achieve top performer status than men, compared to 12 percent more likely in 2015. For managers, the growth in the gender performance gap was even greater, with female managers 22 percent more likely than male managers to be rated as top performers in 2017, up from 7 percent in 2015.

The study also noted that age plays a role in promotions. Despite women being more likely to achieve top performer ratings, under age 40 men receive more promotions than women, with women achieving 9 promotions to every 10 achieved by men. Over age 40, however, this trend inverts, with women receiving more promotions than men.

Additionally, despite the higher likelihood of women being top performers, the study said there is a considerable gap between the proportion of men who are managers and women who are managers. In 2017, 18 percent of men held manager positions compared to only 12 percent of women. Given managers on average earn two times the salaries of non-managers, this gap contributes significantly to the overall gender wage gap

Overall, said the study, despite much media attention, US enterprises are not making collective progress towards closing the gender pay gap. Although female workers are increasingly outperforming their male counterparts, and although female managers are 22 percent more likely to be high performers than male managers, access to manager positions remains biased towards men. At the same time, while some might assume the Millennial generation will overcome this bias, the opposite is true, the study said, with promotions for workers under age 40 being biased towards men.

Leading management consultant Peter Drucker is famously credited with saying, “If you can’t measure it, you can’t improve it.” This is certainly true with gender equity: despite being an issue of incredible focus and debate for employers and lawmakers, the study noted that employers still struggle to understand how to achieve gender equity and, therefore, make little progress.