*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19751
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19860
19870
19880
19890
199010
19916
19929
19932
199410
19956
19968
19979
19985
19997
200025
200113
200211
200324
200419
200510
20061
20073
20088
20095
20102
201110
201211
20136
20140
20150
20160
20170
Total221