Timeline for all types of items produced by
Kohgaku-Sha Co.,Ltd.

Year	Items
1979	5
1980	17
1981	40
1982	48
1983	24
1984	68
1985	76
1986	34
1987	1

313 items with a valid date were considered for this timeline (83.69% of the total)
61 items with an invalid date.

Help us in our quest to find exact dates for:

198?: 61 items.