It's a little funny to see that at the moment every active player is ahead of every retired player (if we consider Ferrero retired).
Djokovic' comeback will one again vault Nastase into first among those with one stretch only. He's lost that distinction many times but always regained it.
That really says a lot about how powerful this era actually is. Certainly to me, I don't care if it does the same to others.
Federer being so dominant helps Nadal's numbers in this case. If he'd had less of a stranglehold on the #1 ranking then Nadal might have stolen it a few times in '05-'07. Even though he'd have more weeks at #1 it would be over 3,4,5+ stretches so his "efficiency" would fall.