How much Topps paid Shawon Dunston every year

1985 $250
1986 $250
1987 $575
1988 $500
1989 $500
1990 $500 (+ $75 bonus)
1991 $500 (+ $75 bonus)
1992 $500 (+ $75 bonus)
1993 $500 (+ $75 bonus)
1994 $500 (+ $75 bonus)
Why did he get paid more in 1987? Maybe he got the $75 signing bonus as part of his main payment.

Source: ebay auction by Topps. I don't think Topps could ever become a paper-less company. Every single internal document they have can be sold for money.