*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19802
19810
19820
19835
19840
19850
19869
19870
19880
19891
19901
19910
19925
19934
19943
19955
19961
19972
19982
19990
20000
20011
20021
20032
200444
20056
20063
20070
200811
20090
201020
201129
20120
20131
20142
20150
20162
20170
Total162