*Excludes Observations that spanned multiple years

Pre 197011
19700
19710
19720
19730
19740
19750
19760
19770
19780
19791
19800
19811
19820
19830
19841
19852
19860
19870
19880
19890
19902
19910
19923
19934
19944
19954
19961
199727
19980
19990
20000
20010
20021
20031
20040
20050
20060
20070
20080
20090
20100
20110
20120
20131
20140
20150
20160
20170
Total64