Based on a 2016 survey: Factors in OA Decision (figure 12) *
Also "'Funding agencies expect it,' highlighting a gap in the options included in the survey." **
* From: Heaton, R., Burns, D., & Thoms, B. (2019). Altruism or Self-Interest? Exploring the Motivations of Open Access Authors. College & Research Libraries, 80(4), 485. doi:https://doi.org/10.5860/crl.80.4.485
** See also: Tri-Agency Open Access Policy on Publications and FAQ: What is OA & Why is it important?
Also worth noting:
Significance of Supervisor or Research Mentor Influence to Publish OA (figure 8)