*Excludes Observations that spanned multiple years

Pre 197015
19700
19710
19721
19732
19740
19751
19761
19770
19781
19790
19800
19811
19820
19831
19842
19850
19860
19871
19880
19890
19901
19911
19921
19931
19940
19952
19960
19971
19980
19991
20000
20010
20020
20030
20040
20050
20060
20073
20081
20090
20104
20110
20120
20130
20140
20150
20160
20170
Total42