SQL Server 2014

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create table yourtable (country varchar(100), value varchar(100));
insert into yourtable values ('FR',NULL);
insert into yourtable values ('FR',1);
insert into yourtable values ('FR',3);
insert into yourtable values ('MA',5);
insert into yourtable values ('MA',NULL);
insert into yourtable values ('MA',4);
insert into yourtable values ('ES',9);
insert into yourtable values ('ES',10);
insert into yourtable values ('ES',NULL);
9 rows affected

SELECT country,
    val = 
    STUFF (
        (SELECT   
                ',' +value  
        FROM yourtable
  WHERE value IS NOT NULL AND y1.country = country
        FOR XML PATH('')
  
  ), 1, 1, ''
  
    )
FROM yourtable y1
GROUP by country
ORDER BY country


country
val


ES
9,10

FR
1,3

MA
5,4