*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19791
19801
19811
19820
19830
19840
19850
19860
19870
19880
19890
19900
19910
19920
19930
19946
19952
19967
19973
19982
199924
20001
20010
20022
20030
20044
20051
200641
20076
20083
200911
201012
20110
20125
20130
20145
20150
20160
20170
20180
Total138