*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
197258
197320
19740
19750
19760
19770
19780
19790
19801
19810
19820
19830
198413
198517
198610
19871
198815
19896
199021
199135
199216
19939
19942
19955
19965
19970
19980
199933
200011
200113
20021
20030
20040
20050
20060
20071
20088
20090
20109
20119
20121
20130
20142
20150
20163
20170
20180
Total325