*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19801
19810
19820
19834
19840
19850
19861
19870
19880
19897
19900
19910
19921
19935
19942
19952
19961
19972
19981
19994
20002
20018
20020
20030
200430
200513
20060
20070
20088
20090
201058
201170
20129
201313
20148
20151
20162
20170
Total253