Like others have said, it is tough to say. Summer jobs and some work study from 8th grade through graduating law school. 8 years of full time work exceeding social security limits. 15 years of "half-time" at best, adjunct faculty work while raising kids. Then, once the eldest hit college and the youngest had his driver's license, 9 years of full time work in excess of social security limits. So either 17, or 36 years?
DW was, with a few exceptions, always our primary wage earner. She had a lot of part time and student jobs until after her second year of med school, then started working in earnest by moonlighting beginning the second year of her residency... True full time work after residency for 27 years, 26 of which were in excess of Social security limits.