UNIX for Beginners Questions & Answers

I am using DB2 v9 and trying to get country values in comma seperated format using below query

Code:

SELECT  distinct LISTAGG(COUNTRIES, ',') WITHIN GROUP(ORDER BY EMPLOYEE)  
FROM LOCATION ;

Output Achieved 
MEXICO,UNITED STATES,INDIA,JAPAN,UNITED KINGDOM,MEXICO,UNITED STATES

The table "LOCATION" has multiple columns apart from Employee and Country and hence i cant group on countries to remove duplicate countries values .
Is there a way to remove dups to get only countries once using above query with modification .

Code:

Expected Output  ( Should exclude MEXICO,UNITED STATES as these two countries are duplicated) 
MEXICO,UNITED STATES,INDIA,JAPAN,UNITED KINGDOM

Any help appreciated.