*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19731
19740
19758
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19860
19870
19880
19890
199013
19916
199215
19933
199410
19953
19967
19972
19987
199910
200011
200111
20026
200320
200413
200518
20068
20077
200819
200914
201015
20113
201210
20130
20140
20150
20160
20170
Total240