*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19724
19732
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19843
198511
19861
19877
198818
19896
199012
199117
19922
19939
19943
19950
19961
19970
19980
19993
20007
20011
20022
20030
20040
20050
20061
20070
20080
20090
20100
20110
20120
20132
20140
20150
20160
20170
20182
Total114