*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19781
19790
19800
19810
19820
19830
19840
19850
19860
19870
19880
19890
19900
19910
19921
19930
19940
19951
19960
19971
19980
19990
20000
20011
20021
200315
20041
20050
20061
20070
20080
20090
20100
20110
20120
20130
20140
20150
20160
20170
Total23