Timeline for all types of items produced by
Science 451

Year	Items
1984	1
1985	1
1986	1
1987	10
1988	39
1989	19
1990	19
1991	4
2005	2

96 items with a valid date were considered for this timeline (84.21% of the total)
18 items with an invalid date.

Help us in our quest to find exact dates for:

19??: 18 items.