*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19771
19782
19790
19800
19810
19820
19833
19840
19851
19860
19870
198821
198912
199010
19919
199214
199331
199411
199520
19968
199723
199853
199931
20002
200111
20024
200318
200429
200511
20068
200711
20087
200910
20104
20116
20120
20130
20140
20150
20169
20170
Total380