Windows was the most used desktop OS for development before WSL. Here's the 2015 Stack Overflow survey, which also includes the 2014 and 2013 results for comparison [1].

Here's the 2021 survey's OS results [2]. It shows higher WSL usage than the AoC survey, but still only 3%.

[1] https://insights.stackoverflow.com/survey/2015#tech

[2] https://insights.stackoverflow.com/survey/2021#section-most-...