*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19853
198610
198713
19886
19891
19902
199132
19927
19936
19941
19955
19960
199713
19981
199912
200073
200186
200234
20032
20042
20053
20060
20070
20081
20090
20102
20110
20122
20135
20143
20157
20162
20172
20180
Total336