How To Count All Responces in Survey List Programmatically

I am trying to Count All Responces in Survey List Programmatically by using Camel query ........

i have done in below code 1)bind the question 2)bind the choice field(response of single user )

and now trying to count all users responses and calculate percentages of responses programmatically

foreach (SPListItem item in collitem) { string v = new SPFieldUserValue(web, item["Author"].ToString()).User.ToString(); HtmlGenericControl que = new HtmlGenericControl("p");

var fields = item.Fields;
foreach (SPField field in fields)

{ if (field.Type == SPFieldType.Choice) {

    SPFieldChoice choiceField;
   choiceField = (SPFieldChoice)field;
    que = new HtmlGenericControl("p");
   que.InnerHtml = field.Title + "</br>";

   SPQuery responseQuery = new SPQuery();

responseQuery.Query = @"

    <IsNotNull><FieldRef Name='" +  field.InternalName + "' /></IsNotNull></Where>";

                            var res = list.GetItems(responseQuery);

                            foreach (SPListItem itm in res)
                            {
        que.InnerHtml += "Answer: " + itm[field.InternalName].ToString();


                            }


                            resultDiv.Controls.Add(que);

                            this.Controls.Add(resultDiv)
              }
      }
 }