*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19741
19750
19760
19770
19780
19790
19800
19811
19820
19831
19840
19852
19860
19870
19880
19892
19900
19911
19920
19930
19940
19950
19960
19970
19980
19993
20002
20011
20024
20030
20040
20050
20060
20070
20080
20090
20100
20110
20121
20132
20140
20150
20160
20170
Total21