*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19753
19761
19770
19780
19791
19803
19810
19820
19830
19840
19850
19860
19870
19880
19890
19909
19916
19926
19932
19946
199515
19966
19970
19982
19998
200010
200112
20025
200324
200429
200516
20066
200711
200820
20090
201025
20110
20120
20130
20140
20150
20160
20170
Total226