*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19862
19870
19885
198912
19905
19912
19921
19930
19943
19951
19963
19977
19981
19994
20002
20012
20021
20030
20040
20050
20060
20070
20082
20090
20102
20115
20120
20130
20140
20150
20160
20170
Total60