*Excludes Observations that spanned multiple years

Pre 19701
19700
19710
19720
19730
19740
19750
19760
19770
19781
19790
19800
19810
19820
19830
19840
19850
19860
19871
19880
19890
19900
19910
19921
19932
19942
19951
19960
19971
19981
19990
20003
20010
20021
20030
20040
20051
20061
20071
20080
20090
20100
20110
20120
20130
20140
20150
20160
20170
Total18