*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19841
19853
19863
198745
198812
198913
199010
19915
19922
19932
19944
199543
19960
199717
19987
19992
200017
20013
20020
20035
20040
20054
20061
200740
200818
200914
20107
20114
20120
20130
20140
20152
20160
20170
Total284