Start by naming the Top 10 (incl ties) point leaders for 1980. For 1981, name the Top 10 assuming the 1980 Top 10 had Retired. For 1982, assume those in the 1980 & 1981 lists had retired, and so on.
Basically - for a given year, for a player to be in that list they must be among the top 10 scorers for that year NOT INCLUDING those who would've been listed for a previous year in the quiz. So for 1982, you are looking for players who weren't in the 1980 Top 10, nor those who were in the 1981 Top 10 (a Top 10 which excluded the 1980 Top 10)...and so on. So no player will be listed more than once.