*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19860
19870
19883
19890
19900
19910
19920
19930
19942
19950
19960
19971
19980
19991
20001
20013
20021
20030
20040
20051
20060
20070
20080
20090
20100
201117
20120
20130
20145
201510
201645
20170
20180
Total90