*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19791
19800
19810
19820
19830
19840
19850
19860
19870
19880
19890
19902
19910
19920
19938
19943
19952
19961
19975
19982
19991
20000
20010
20024
20030
20040
20050
20060
20071
20080
20090
20100
20110
20121
20130
20140
20150
20160
20170
Total31