Women make up 24% of the workers in science, technology, engineering, and mathematics (or “STEM”) fields in the US, according to Census Bureau data. A new Pew Research Center analysis offers a grimmer statistic to layer on top of that: Half those women—despite comprising a fourth of the workforce—have experienced gender discrimination at work.

Per Pew’s report, most women in STEM, regardless of their level of education, have experienced more work-based gender discrimination and sexual harassment, and have fewer opportunities to succeed, than men. While half of all female STEM workers said they’ve been discriminated against in a professional setting, that number is only 19% for their male counterparts. (And it is 41% for female workers outside of STEM, indicating that the culture of STEM fields pose added difficulties for women.)

The details of the discrimination get starker when broken down into specifics. In response to survey questions, 29% of women said they “were treated as if they were not competent,” as opposed to 4% of men; 20% said they “experienced repeated, small slights at work,” compared to 4% of men; 11% of women felt isolated in their workplace, while that applied to 5% of men, according to the report, which was published this week and based on a survey of 4,814 American workers,.

More than 50% of women in STEM said they “feel the need to prove themselves at work”—a number that jumped to 79% for women who work in majority-male fields, such as mechanical engineering or sales engineering (which are only 8% and 7% female, respectively). Three-quarters of women in computer jobs said they have experienced gender-related discrimination.

To those who follow politics or education news, none of this will be—sadly— especially revelatory. The STEM fields have been shown to be riddled with instances of overt or implicit sexism, from STEM students describing female professors more negatively than male ones to certain academic tests at an early age being skewed toward men. And all of that is before women even make it to STEM professions themselves, where they often face biases in hiring and promotion.

Underrepresentation is clearly both a reason for, and a result of, the discrimination. Pew’s study offers no panacea for the imbalances, but it does, by laying the numbers out, provide a new data-driven impetus to policymakers, educators, and employers to get more girls into science.