*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19751
19760
19771
19780
19790
19800
19810
19820
19831
19840
19850
19861
19870
19881
19890
19900
19915
19922
19931
19940
19951
19960
19973
19980
19990
20000
20010
20020
20032
20040
20051
20060
20070
20081
20090
20100
20111
20120
20130
20140
20150
20160
20170
Total22