*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19771
19782
19790
19800
19810
19820
19833
19840
19851
19860
19870
198821
198912
199010
199110
199214
199332
199411
199521
19968
199723
199854
199933
20002
200111
20024
200320
200434
200517
200615
200714
20087
200914
20107
201115
20129
201316
201417
201512
201634
201716
20180
Total520