*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
19920
19933
19940
19950
19961
19971
19981
19993
20003
20011
20022
20035
20043
20057
200612
20074
20084
20090
20108
20110
20124
20139
20143
20152
20160
20170
20180
Total76