*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19801
19810
19820
19831
19840
19851
198611
19870
19880
19891
19902
19913
19920
19934
19948
199513
19961
19975
199823
19992
20007
20019
20028
20034
200491
2005111
20068
20073
20089
20095
201020
201115
20124
20130
20145
201544
20163
20173
Total425