*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19860
19870
19880
19890
19900
19910
19921
19931
19942
19950
199616
19975
19980
19992
200011
20010
20020
20030
20040
20050
20060
20070
20080
20092
20101
20110
20120
20130
20141
20150
20160
20170
Total42