*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19781
19790
19800
19810
19820
19830
19840
19854
19861
19871
19880
19892
19901
19912
19922
19931
19940
19950
19961
19970
19980
19990
20002
20010
20020
20030
20040
20050
20060
20070
20080
20090
20100
20110
20121
20130
20140
20150
20160
20170
20180
Total19