*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19861
19871
19880
19891
19900
19910
19920
19930
19941
19954
19961
19970
19980
19991
20003
20010
20020
20030
20042
20052
20063
20076
20086
200915
201066
201170
2012100
201369
201450
201576
20160
20170
20180
Total478