*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19831
19841
19850
19860
19871
19884
19891
19903
19911
19922
19931
19946
19952
19961
19973
19981
19990
20008
20017
20023
200313
20047
200517
200616
200713
200820
200917
201030
201139
201223
201320
201418
201519
20166
20170
20180
Total304