I would like to thank Litotes and Freak3 for the intriguing idea and work.
The "successive" winners obviously dominate the second stat. Federer and Borg winning Roland Garros (Borg), Wimbledon (both), and US Open (Federer) so many times in a row puts them ahead of the pack in that category. They are the only ones who defended them over 50% of the time.
But what I found interesting is how little others have been able to defend their Slam titles. Ivan Lendl is the only other one (with considerable amount of Slams) who was able to defend them at 50% of the time. Sampras, Nadal, John Mc Enroe, are all below 50%.
Wilander has 7 titles and only defended them successively once.
Agassi is 8 and 1.
Connors is 8 and 1.
It shows how hard it is to defend a Slam title.