*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19861
19870
19880
19890
19900
19910
19922
19930
19947
19950
19963
19973
19980
19998
20001
20010
20020
20030
20040
20050
20061
20070
20080
20090
20100
20111
20120
20130
20140
20150
20160
20170
Total27