Facebook SDK Json Parsing with foreach loop not updating

Hi Guys I wonder if you can help me,

I know the Facebook SDK isn't popular around here but i think the cause of this problem is more the foreach loop and not anything to do with the SDK.

The foreach loops works fine, it updates the Text as it supposed to when the function is run, but if you run the function again, it's supposed to just update the Text and not keep adding the same line to it everytime the Function is run. What am I doing wrong here?

     public void QueryScores(){
 
         FB.API ("/app/scores?fields=score,user.limit(30)", HttpMethod.GET, ScoresCallback);
     }
 
     private void ScoresCallback(IGraphResult result){
 
         Debug.Log (result.RawResult);
 
         var dict = Json.Deserialize (result.RawResult) as Dictionary<string,object>;
         ScoresList = dict ["data"] as List<object>;
 
         foreach (object score in ScoresList)
         {
             var entry = (Dictionary<string,object>) score;
             var user = (Dictionary<string,object>) entry["user"];
 
             ScoresDebug.text = ScoresDebug.text + "UN: " + user["name"]+ " - "+entry["score"]+ ", ";
 
         }
 
     }

Please can someone lend me a hand! Thanks guys.

Regards,