*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19731
19740
19750
19760
19771
19780
19790
19800
19810
19820
19830
19840
19851
19860
19874
19889
19893
199014
19919
199212
19939
19945
199519
19969
199722
19983
19995
20003
20011
20021
20036
20042
20052
20063
20071
20082
20090
20100
20110
20120
20130
20140
20151
20160
20170
Total148