*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19781
19790
19800
19810
19820
19835
19840
19850
19860
19870
198828
19890
19900
19913
19925
19931
19940
19955
19962
19977
19985
19999
20000
20011
20020
20031
20040
20057
20062
20070
20081
20090
20100
20110
20120
20130
20140
20150
20160
20170
Total83