*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19801
19810
19821
19830
19840
19851
19861
19870
19880
19890
19905
19910
19922
19931
19943
19950
19960
199714
19982
19990
20000
20010
20026
20031
20041
20050
20060
20070
20081
20090
20100
20110
20120
20130
20140
20150
20160
20170
Total40