*Excludes Observations that spanned multiple years

Pre 197022
19700
19710
19720
19730
19740
19750
19760
19771
19781
19790
19801
19810
19820
19831
19842
19850
19860
19870
19880
19890
19900
19910
19920
19930
19940
19951
19962
19972
19982
19993
20002
20012
20022
20032
20042
20052
20062
20072
20082
20092
20102
20112
20122
20130
20140
20150
20160
20170
Total64