*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
197215
19731
19740
19750
19760
19770
19780
19790
19800
19810
19820
19831
19840
19850
19860
198710
19887
198912
199056
199154
199240
199329
19943
199526
19960
19978
19983
199910
20002
20013
20021
20030
20042
200511
20060
20070
20082
20090
20100
20113
20122
20130
20140
20151
20166
20172
20180
Total310