*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19860
198715
198830
19890
19907
19919
19923
19935
19940
199532
19960
19970
199812
199913
200011
200110
20021
20031
20040
20050
20060
20070
20080
20090
20102
201119
20120
20130
20140
20152
20160
20171
20180
Total173