*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19751
19762
19770
19780
19791
19801
19810
19820
19832
19844
198516
19869
198710
19886
19892
19902
19911
19922
19932
19940
19950
19960
19972
19980
19993
200043
20013
20022
200340
200439
200585
2006104
200769
200871
2009163
2010135
2011154
20120
20130
20140
20150
20160
20170
Total974