*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19791
19800
19811
19821
19831
19842
19850
19867
198712
198813
198910
19908
19916
199220
19938
19948
199537
19960
19979
19981
19996
20003
20019
200215
20036
20042
200526
20066
20077
200810
20091
20100
201113
20120
20130
20140
20150
20169
20170
Total258