*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19731
19740
19750
19760
19770
19781
19791
19800
19810
19820
19831
19840
19850
19860
19870
19883
19893
19903
19919
19922
19935
19941
19951
19960
19971
19986
19990
20000
20010
20020
20030
20040
20050
20060
20070
20080
20090
20100
20110
20120
20130
20140
20150
20160
20172
20180
20190
20200
Total40