*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19801
19810
19820
19830
19840
19850
19860
19870
19881
19890
19900
19911
19920
19933
19946
19952
19964
19978
199831
19999
20000
20011
20023
20030
20046
20051
20063
20070
20085
20096
20104
20114
20120
20130
20140
201513
20168
20178
20180
Total128