*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
19871
19880
19890
19900
19910
19920
19930
19942
19950
19960
19971
19982
19996
20007
20010
20023
20031
20045
200510
20060
20070
20085
20090
20100
20111
20123
20130
20140
20150
20161
20170
Total48