*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19831
19840
19850
19860
19871
19885
19897
19901
19915
19921
199319
19944
19955
19961
19970
19981
19990
20000
20010
20020
20030
20040
20050
20060
20070
20086
20090
20100
20110
20120
20130
20140
20150
20160
20170
Total57