*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19728
19733
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19861
19875
198841
19893
199065
1991142
199246
199328
19942
199539
19961
199725
19983
199923
200011
200111
20020
20033
200434
20057
20060
20072
200816
20090
201019
201131
20123
20133
20140
20150
20164
20170
20180
Total579