Occupational Requirements Survey - U.S. Bureau of Labor Statistics

The Occupational Requirements Survey (ORS) publishes job-related information on physical demands; environmental conditions; education, training, and experience; as well as cognitive and mental requirements. The job requirements reflect those necessary for workers to perform critical tasks in support of the critical job functions, and not the capabilities of individual workers. Credentials include training time required as a condition of hiring, which often results in certifications, licenses, or educational certificates and are part of the education, training, and experience requirements. The published estimates reflect the percentage of workers with credential requirements and the time necessary to obtain them.

https://www.bls.gov/ors/factsheet/credentials.htm