*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19831
19840
198510
19868
19875
198828
19890
199012
19915
199222
19936
19944
199548
19964
19971
19980
199957
200024
20014
20026
20031
20041
20051
20066
20070
20080
20091
20100
20112
20120
20132
20140
20151
20161
20171
20180
20190
20200
Total262