make SOAP POST content and reading SOAP response

Program.cs

using System;
using System.Xml.Linq;
using System.IO;
using System.Text;
using System.Collections.Generic;

namespace runthis
{
    class Program
    {
        static void Main(string[] args)
        {
            //SOAPrequest();
            SOAPread();
        }

        static void SOAPrequest()
        {
            XDocument content = new XDocument(new XDeclaration("1.0","utf-8", null));
            XElement env = new XElement("Envelope");
            XElement body = new XElement("Body");

            XNamespace xns = "http://tempuri.org/";
            XElement action = new XElement(xns + "GET_YEAR");
            action.Add(
                new XElement(xns + "USERID", _usr),
                new XElement(xns + "PASSWORD", _pwd),
                new XElement(xns + "SITEID", _siteId),
                new XElement(xns + "CATEGORY", "3")
            );
            
            body.Add(action);
            env.Add(body);
            content.Add(env);

            StringWriter sw = new Utf8StringWriter();
            content.Save(sw, SaveOptions.None);
            Console.WriteLine (sw);
        }

        static void SOAPread()
        {
            string response = "<?xml version=\"1.0\" encoding=\"utf-8\" ?><soap:Envelope xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\"" +
            " xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\">" + 
            "<soap:Body><GET_YEARResponse xmlns=\"http://tempuri.org\"><year>2020</year></GET_YEARResponse></soap:Body></soap:Envelope>";

            XDocument doc = XDocument.Parse(response);
            XNamespace ns = "http://tempuri.org";
            IEnumerable<XElement> responses = doc.Descendants(ns + "GET_YEARResponse");
            foreach (XElement res in responses)
            {
                Console.WriteLine((string)res.Element(ns + "year"));
            }
        }
    }
    public class Utf8StringWriter : StringWriter
    {
        public override Encoding Encoding { get { return Encoding.UTF8; } }
    }
}