*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
19880
19890
19900
19910
19920
19930
19940
19950
19960
19970
19980
19991
20001
20011
20020
20032
20041
20053
20063
20071
20083
20090
20100
20110
20120
20131
20140
20150
20160
20170
Total18