*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19831
19840
19851
19866
19871
19886
198918
19901
199112
19926
199333
199412
199528
19965
19979
19981
199912
20006
20012
20029
20039
20041
200530
20066
20070
20080
20091
20101
201115
20120
20130
20142
20152
20162
20171
20180
Total239