*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19791
19800
19810
19820
19831
19840
19850
19864
198713
19881
19892
19900
19910
19921
19930
19940
19950
19964
19971
19980
19991
20000
20011
20021
20031
20041
20052
20060
20070
20083
20090
20100
20110
20120
20130
20140
20150
20161
20170
Total39