If the basketball cards you acquired have the tear-off name tabs
at the top, there are key numbers that determine upon which
season the cards are based.  Each card will have 35's OR 36's at a
particular dice roll in all three result columns (P, D, & S) on the
card.  Here are the seasons with the corresponding dice roll at
which you will find the 35's or 36's:
 
1965-66 - 65
1966-67 - 26
1967-68 - 21
1968-69 - 46
1969-70 - 41
1970-71 - 61
1971-72 - 24
1972-73 - 13
1973-74 - 53
1974-75 - 64
1975-76 - 62
1976-77 - 42
1977-78 - 45
1978-79 - 63
1979-80 - 43
1980-81 - 23
1981-82 - 54
1982-83 - 34
1983-84 - 14
1984-85 - 52
1985-86 - 32
1986-87
 
Any season after 1987-88 and the cards will have a copyright
date at the bottom of each card.  (They may also have the key
numbers, but my records only go up to 1986-87.)  The copyright
date should be the year in which the season represented ended.  
For example, a card with a copyright date of 1990 would be based
on the 1989-90 season.  It is my understanding that the Copyright
Date must reflect the year in which sales of the copyrighted item
were begun.  The 1989-90 season concluded in the Spring of 1990,
and we would have begun selling the sets by July or August of that
year.