*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19831
19840
19850
19860
19874
19882
19890
19900
19910
19920
19930
19940
19959
19960
19971
19980
19991
20000
20010
20020
20030
20040
20050
20061
20079
20081
20090
201011
20118
20120
20130
20140
20150
20160
20170
Total48