*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19771
19780
19790
19800
19810
19820
19831
19840
19851
19861
19872
198819
19890
19900
19911
19929
19939
19940
19950
19960
19970
19980
19990
20001
20010
20020
20032
20040
20050
20060
20071
20080
20090
20100
20111
20120
20130
20140
20151
20160
20170
20180
20190
20200
Total50