*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19731
19741
19750
19760
19770
19780
19790
19800
19810
19820
19830
19842
19851
19860
19874
19880
19890
19901
19910
19921
19931
19946
199511
19961
19974
19982
19990
20000
20016
20021
200310
20045
20053
20060
20071
20080
20090
20100
20110
20121
20130
20140
20151
20160
20170
Total64