*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19761
19770
19780
19790
19800
19810
19821
19830
19842
19851
19861
19878
19888
198911
199018
199136
199230
199338
199410
199536
19965
199735
19988
19996
20004
200115
20028
20035
200433
200524
20064
20076
20085
20093
201013
201111
20120
20130
20140
20150
20167
20170
Total393