*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19856
19862
19870
19880
19897
19902
19910
19923
19934
19941
199513
19962
199715
19987
19991
20000
20013
20020
20030
20040
20052
20061
20071
20081
20091
20100
20110
20120
20130
20140
20150
20160
20170
Total72