*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19781
19790
19800
19810
19820
19835
19840
19850
19860
19874
198823
19890
19901
19910
19921
19931
19943
19950
19960
19976
19981
19990
20000
20012
20020
20030
20040
20051
20060
20070
20081
20091
20100
20110
20120
20131
20140
20150
20160
20170
Total52