看不懂题意，不明白想实现什么

data test;
input ID $   Variable $  Time;
cards;
1 x 1
1 .  2
1 x 3
1 x 4
1 x 5
1  . 6
1 x 7
1 x 8
2  . 6
2 x 7
2 x 8
3  . 6
3 x 7
3  . 6
3 x 7
3 x 8
3 x 7
3  . 6
;
run;

data test;
set test;
if variable="" then rank+1;
run;

proc sql;
create table test1 as
select *,count(rank) as n from test
group rank;
quit;

data test2;
set test1;
where n>=4 and variable^="";
run;

菜鸟路过，，，