*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
197268
197318
19740
19750
19760
19770
19780
19790
19801
19810
19820
19830
198426
19852
198612
198726
198846
198919
19907
199148
199228
199322
19947
19950
19961
19970
19980
199936
200078
200150
200232
20032
20041
20051
20060
20070
200810
20091
201010
201111
20123
20130
20141
20151
20166
20173
20180
Total577