*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
19870
19880
19890
19900
19916
19920
19930
19948
19954
199613
19974
19986
199915
20000
20014
20022
20035
200421
20055
20062
200710
20082
200922
20100
20111
201210
20132
20140
20150
20162
20170
20180
Total144