*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19861
19870
19880
19890
19900
19910
19920
19930
19940
19950
19960
19970
19981
19990
20000
20013
20020
20032761
2004421
20051775
200620
200741
200812
2009139
20106
20117
20122
20133
201411
20156
201621
201721
20181
Total5252