*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19860
19870
19880
19890
19901
19910
19920
19930
19940
19950
19963
19972
19982
19993
20002
20017
20021
200310
200411
20058
200618
20076
200832
200910
201013
20113
20128
20134
20140
20150
20160
20170
Total144