*Excludes Observations that spanned multiple years

Pre 19703
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19831
19840
19850
19868
19877
19889
19894
19902
199119
199213
19936
19947
199511
199610
19979
19984
19990
20003
20013
20020
20033
20041
20051
20060
20070
200810
20091
201016
201111
20120
20130
20140
20152
20166
20173
20180
Total173