It’s based on PayScale’s year-long survey of 1.2 million users that graduated only with a bachelor degree in the United States.

https://bigthink.com/thinking/philosophy-majors-smarter-make-more-money/

https://www.weforum.org/agenda/2018/07/which-college-degrees-get-the-highest-salaries

Dane: https://www.kaggle.com/datasets/wsj/college-salaries?select=salaries-by-region.csv