The peak of women's representation in computing was ~33% in the early 1980s. Not that much higher than the ~20% we see today. And many of these women in early computing not because it was their first choice, but because the jobs they wanted weren't open to women. Mary Allen Wilkes, for example, wanted to be a trial lawyer but went into computing because no firm she contacted would let women be trial lawyers [1]. This isn't unique to the US, but part of a broader trend of more gender equality being associated with lower rates of women in STEM fields [2].

1. From Clive Thompson's "Coders" chapter 2.

2. https://www.theatlantic.com/science/archive/2018/02/the-more...