*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
19873
19880
198913
199011
199123
199237
199347
199421
199515
19966
199734
199824
199918
20003
20014
20026
20035
200411
200539
20067
20077
20089
200910
20106
20114
20120
20130
20143
20150
20165
20170
Total371