data test;
input id year entry ;
cards;
1 2002 0
1 2003 1
1 2004 0
1 2005 0
1 2006 1
1 2007 0
1 2008 0
1 2009 0
2 2002 0
2 2003 1
2 2004 0
2 2005 0
2 2006 1
2 2007 0
2 2008 1
2 2009 0
;
run;
proc sort data=test; by id descending year; run;
data test01;
set test;
by id descending year;
retain flag;
if first.id then flag=.;
if entry=1 then flag=1;
run;
proc sort data=test01 out=test02; by id year; where flag=1; run;
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