*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
19870
19880
19890
19900
19910
19920
19930
19941
19951
19960
19971
19980
19993
20000
20011
20020
20030
20040
20051
20060
20070
20080
20091
20106
20116
20120
20130
20141
20150
20161
20170
Total24