*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19721
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19851
19860
198725
198881
198910
199051
1991167
199292
199314
19941
199527
19961
19974
19988
1999102
200069
200111
200213
20030
20041
20053
20060
20070
20082
20091
201056
201165
201214
20136
20141
20152
20162
20172
20180
Total833