*Excludes Observations that spanned multiple years

Pre 19701
19700
19710
19720
19730
19740
19750
19760
19770
19781
19790
19800
19810
19820
19830
19840
19851
19860
19876
19881
19890
19900
19910
19921
19931
19942
19954
19960
19971
19980
19990
20000
20010
20020
20030
20040
20050
20060
20070
20080
20090
20100
20111
20120
20130
20140
20150
20160
20170
20181
20190
20200
20210
20220
Total21