*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19801
19810
19820
19830
19840
19850
19868
19878
198810
198917
19902
199112
19921
19939
19948
199543
19962
199711
199815
19997
200022
200110
200211
20036
20048
20057
200612
20076
20086
20096
20106
20116
201212
201312
20149
201511
201613
20178
20180
Total325