*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19862
198710
19880
198910
19906
19913
199220
199331
199423
199593
19965
199735
199843
199926
20005
200133
200219
20031
200418
200544
200612
200710
200812
200911
20103
20114
20120
20130
20140
20150
20162
20171
Total482