Years Before Regeneration:

First Doctor: 63-66 (3 years)
Second Doctor: 66-69 (3 years)
Third Doctor: 70-74 (4 years)
Fourth Doctor: 74-81 (7 years)
Fifth Doctor: 81-84 (3 years)
Sixth Doctor: 84-86 (2 years)
Seventh Doctor: 87-96 (9 years)
Ninth Doctor: 05 (2 months)
Tenth Doctor: 05-10 (4 years)
Eleventh Doctor: 10-13 (3 years)
Eighth Doctor: 96 – 13 (17 years)