*Excludes Observations that spanned multiple years

Pre 19701
19700
19710
19720
19730
19740
19751
19760
19770
19781
19790
19800
19811
19821
19832
19841
19852
198610
198718
198841
198920
199012
199110
199227
199335
199417
199511
199611
199729
199811
19996
20001
20012
200214
20037
200430
200514
20067
200710
200816
20092
201018
201113
201215
20137
20147
201512
201618
201722
20186
Total489