*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19802
19810
19820
19830
19840
19850
19861
19873
19881
198913
19902
19910
199223
199316
19946
199523
19961
19971
199815
19992
20002
20013
20023
20030
200439
200559
20065
20071
200810
20094
20100
20110
20120
20130
20140
20150
20169
20170
Total244