*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19751
19761
19770
19780
19790
19801
19810
19820
19830
19840
19850
19860
19870
19880
19890
19901
19910
19921
19930
19941
19951
19961
199712
19989
19998
200020
200124
200227
200376
200483
2005168
2006151
200756
200877
2009162
2010134
201177
20122
20133
20140
20150
20160
20170
Total1097