Conoco, the world’s biggest independent oil producer, has seen its percentage of female and minority workers climb among its youngest generation of employees, Lance said in an interview from his Houston headquarters on Thursday.

Boosting diversity is a priority at the company, which has 13,000 employees, Lance said. Women make up a quarter of his eight-member executive leadership team and account for four of 10 seats on the board of directors. Conoco didn’t see a rise in sexual harassment complaints last year, he said, even as high-profile cases made headlines.

Still, there’s work to be done, especially in making it easier for women to sustain a career in the business, Lance said.

“This industry is not an industry that has done well at attracting females and then retaining them as they go forward raising a family,” Lance said. “The challenge for our business, our company and our industry is retention over the course of 20 to 30 years.”

In 2016, 27% of Conoco’s employees were women, according to data compiled by Bloomberg (BLOOMBERG). A report that year from the American Petroleum Institute, the industry’s trade group, found that women accounted for 17% of the workforce at oil, natural gas and petrochemical companies.

Seventeen percent of Conoco’s top leadership and 28% of its professional employees were women in 2016, according to the company’s Sustainability Report. Minorities made up 23% of the workforce.