*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19860
19870
19880
19890
19900
19910
19920
19930
19940
19951
19960
19972
199810
19994
20002
20010
20022
200383
20044
200539
20061
20071
20081
20091
20101
20111
20122
20131
20140
20150
20161
20173
20180
Total160