*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19801
19810
19820
19830
19840
19850
19860
19871
19881
19890
19900
19911
19920
19933
19946
19954
19964
19978
199833
19999
20000
20011
20023
20030
20046
20051
20064
20070
20086
20098
20105
20115
20121
20132
20144
201510
20166
201711
20180
Total144