Following a 2017 change to U.K. law that required firms with 250 or more employees to report their gender pay gaps, Zaha Hadid Architects (ZHA) has released data showing their female employees were paid 20.86 percent less on average in 2017. The firm’s pay gap reflect a general trend across the industry, although some firms have an average pay gap as low as ten percent, according to the Architect’s Journal.

Through an in-house report produced by ZHA (available here), the firm compared the median incomes earned by both men and women–the middle-most figure–to calculate the pay disparity. Men were paid 20.86 percent more on average and received bonuses 64.94 larger on average, while only 75.6 percent of women received a bonus in 2017 versus 84.05 percent of men at the studio. Across the firm’s 310 U.K. employees, 37 percent are women.

ZHA has chalked this imbalance up to the higher percentage of men in leadership positions, who have been with the firm the longest and command bonuses that are tied to the company’s revenue. According to the report:

“This pay gap exists because [a] higher proportion of our longest-serving team members who grew the practice with Zaha Hadid over the past 30 years are male and have continued to lead the company since her passing in 2016. We therefore currently have a smaller proportion of women than men in higher paid senior positions.”

In an effort to address these imbalances, ZHA has increased the company’s maternity pay and partnered with the Architect’s Journal’s Women in Architecture forum. A mentorship program has also been established throughout the firm.

Still, even as firms are motivated by public exposure to address the imbalances in pay between men and women, studies have shown that the pay gap is widening. Foster + Partners, AECOM, and other big names have disclosed similar figures, though they claim that the imbalance also results from having more men at the top and not as an equal pay issue. Foster + Partners has, for their part, also committed to broadening gender diversity at the senior level, while AECOM pledged to create a more inclusive workforce.

Transparency in the field has become a pressing topic as of late, as more and more women have been coming forward with their experiences regarding harassment, discrimination, and general misconduct.

A full list of U.K. companies who have disclosed their pay and bonus gap data is available here. Companies have until April 4 to disclose their pay gap report, and more industry figures will be forthcoming.