*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19791
19801
19811
19820
19830
19841
19854
19860
19876
198810
19893
19906
19913
199227
199310
19946
19957
19962
199712
19987
19999
200016
20012
20021
20031
20042
200514
20060
20078
20081
20096
20103
20111
20123
20131
20140
20150
20160
20170
Total175