*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
198514
19861
19874
19888
19893
199011
19918
199210
19937
19940
19950
19960
19970
19980
19996
200020
200124
20024
20030
20040
20051
20060
20070
20081
20091
20101
20110
20120
20131
20140
20151
20161
20171
20180
Total128