*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
19910
19923
19930
19940
199512
19960
19971
19980
19992
20000
20010
20026
20030
20042
20050
20062
20070
20081
20090
20100
20111
20120
20130
20140
20150
20161
20170
Total31