*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19861
19871
19881
19890
19900
19910
19920
19930
19940
19950
19960
199711
19980
19990
20001
20010
20020
20032
20040
20050
20060
20070
20080
20090
20100
20110
20120
20130
20141
20150
20160
20170
Total18