The %-column in the table is an average percentage of how much the player scored in each of the seven seasons in comparison to each seasons benchmark number. Something users over at HFBoards.com have worked on, although there are many slightly different versions of it out there, all arbitrary.
Basically the benchmark for each season is never the number one scorer(If it’s not a tie as in Jagr and Lindros in 1994/95) due to the outlier risk, not seldom the case when Wayne Gretzky won his Art Ross trophies. It is just not fair when others gets to be compared to Sidney Crosby. Most often it is the number two scorer if that player is not too much of an outlier as well. For example, in 2013/14 the benchmark is Ryan Getzlaf’s 87 points since Claude Giroux trailed at third with 86. There is also a small weighting being made in this version to ever so slightly give gains to the more average seasons of the seven in question, this becouse the creators felt that those are somewhat more relevant than a possible outlier season or two on either end of the spectrum.
The whole system gives props for good health becouse its not points/game we are talking about.
Active players obviously still have the chance to better their score by kicking out their worst season of this seven season prime.