*Excludes Observations that spanned multiple years

Pre 19705
19700
19710
19720
19730
19740
19750
19762
19770
19780
19790
19800
19810
19820
19830
19840
19850
19860
19871
19881
19891
19900
19911
19921
19930
19940
19951
19961
19970
19981
19993
20002
20010
20020
20030
20040
20050
20060
20071
20080
20094
20104
20112
20120
20130
20140
20150
20160
20170
20180
Total31