*Excludes Observations that spanned multiple years

Pre 19700
19700
19711
19720
19730
19740
19750
19760
19770
19781
19790
19801
19810
19820
19830
19840
19850
19860
198712
198832
19891
199019
199119
199216
19932
19940
199529
19964
19977
19982
199919
20000
20010
20021
20030
20040
20050
20060
20071
200825
200912
20101
20110
20120
20131
20140
20150
20161
20170
20180
20190
20201
20210
Total208