如何从C#数据表向json字符串中添加自定义的Key，values

我的预期输出是：

{
        key: "user",
        values: [
            {
                "label" : "A" ,
                "value" : 29.765957771107
            } ,
            {
                "label" : "B" ,
                "value" : 0
            } ,
            {
                "label" : "C" ,
                "value" : 32.807804682612
            } ,
            {
                "label" : "D" ,
                "value" : 196.45946739256
            } ,
            {
                "label" : "E" ,
                "value" : 0.19434030906893
            } ,
            {
                "label" : "F" ,
                "value" : 98.079782601442
            } ,
            {
                "label" : "G" ,
                "value" : 13.925743130903
            } ,
            {
                "label" : "H" ,
                "value" : 5.1387322875705
            }
        ]
   }

但是我得到的是

{  
"user":[  
  {  
     "label":"122",
     "value":"387"
  },
  {  
     "label":"136",
     "value":"402"
  },
  {  
     "label":"59T",
     "value":"34372"
  },
  {  
     "label":"601",
     "value":"2970"
  },
  {  
     "label":"APA",
     "value":"1"
  },
  {  
     "label":"B01",
     "value":"3376"
  },
  {  
     "label":"B11",
     "value":"5490"
  },
  {  
     "label":"C67",
     "value":"5629"
  },
  {  
     "label":"CCS",
     "value":"1671"
  },
  {  
     "label":"F31",
     "value":"12"
  },
  {  
     "label":"F32",
     "value":"4459"
  },
  {  
     "label":"FC0",
     "value":"18780"
  },
  {  
     "label":"FMD",
     "value":"15235"
  },
  {  
     "label":"GLC",
     "value":"3202"
  },
  {  
     "label":"GRZ",
     "value":"336"
  },
  {  
     "label":"HAM",
     "value":"651"
  },
  {  
     "label":"OP1",
     "value":"12771"
  },
  {  
     "label":"OP2",
     "value":"2065"
  },
  {  
     "label":"OP3",
     "value":"1519"
  },
  {  
     "label":"OZW",
     "value":"2866"
  },
  {  
     "label":"RAO",
     "value":"2907"
  },
  {  
     "label":"S00",
     "value":"17467"
  },
  {  
     "label":"SIN",
     "value":"13898"
  },
  {  
     "label":"SLE",
     "value":"2549"
  },
  {  
     "label":"STR",
     "value":"542"
  },
  {  
     "label":"TCG",
     "value":"3628"
  },
  {  
     "label":"TCK",
     "value":"1487"
  },
  {  
     "label":"TCM",
     "value":"4729"
  },
  {  
     "label":"TCW",
     "value":"6348"
  },
  {  
     "label":"TSS",
     "value":"1543"
  },
  {  
     "label":"VA1",
     "value":"1139"
  },
  {  
     "label":"VA2",
     "value":"2370"
  },
  {  
     "label":"VA6",
     "value":"1556"
  },
  {  
     "label":"YC1",
     "value":"443"
  },
  {  
     "label":"YC2",
     "value":"37"
  },
  {  
     "label":"YC4",
     "value":"1"
  },
  {  
     "label":"YC6",
     "value":"1"
  },
  {  
     "label":"YMW",
     "value":"36"
  }
 ]
 }

我的c#类如下：

    public class Propm2345
    {
        public string label { get; set; }
        public string value { get; set; }
    }
    List<Propm2345> p911 = new List<Propm2345> { };
    [WebMethod]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json, UseHttpGet = false)]
    public string get_OPC_Site_view()
    {
        string sit = "S00";
        //select label, value from getOPC_site_count_for_chart
        string query = "select label, value from getOPC_site_count_for_chart";
        SqlCommand cmd = new SqlCommand(query);
        DataSet ds = GetSITData1(cmd);
        DataTable dt = ds.Tables[0];
        foreach (DataRow item in ds.Tables[0].Rows)
        {
            Propm2345 pp = new Propm2345();
            pp.label = item["label"].ToString();
            pp.value = item["value"].ToString();
            p911.Add(pp);
        }
        JavaScriptSerializer jss = new JavaScriptSerializer();
        var obj = new { user = p911 };
        string ss = jss.Serialize(obj);
        return ss;           
    }

使用上面的代码，我得到了正确的输出，但我想添加自定义根键和值jsut来馈送nvd3图表。请帮助实现预期的json输出。

JavaScriptSerializer jss = new JavaScriptSerializer();
var obj = new { key = "user", values = p911 };
string ss = jss.Serialize(obj);
return ss;