*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19831
19840
19850
19860
19871
198830
19891
19906
19912
19928
19933
19948
19957
199611
19977
19985
19991
20001
20012
20021
20032
20040
20051
20060
20071
20081
20090
20103
20114
20120
20130
20141
20150
20165
20170
20180
Total113