William Hartnell was 67, Patrick Troughton was also 67, and Jon Pertwee was 76.
I think he meant how old were all eleven in 1975, 1987 and 1996.
1975: 1 was 67, 2 was 55, 3 was 56, 4 was 41, 5 was (barely) 24, 6 was 32, 7 was 32, 8 was 16, 9 was 11, 10 was (barely) 4, 11 was -7 (if that can be counted)
1987: 1 was deceased, 2 was 67, 3 was 67, 4 was 53, 5 was 35, 6 was 44, 7 was 44, 8 was27, 9 was 22, 10 was 15, 11 was 5
1996: 1 was gone, 2 was gone, 3 was 76, 4 was 62, 5 was 45, 6 was 52, 7 was 52, 8 was 36, 9 was 32, 10 was 25, 11 was 13