Text to Full Width Latin in C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace FullWidthConverter
{
    public partial class Form1 : Form
    {
        private Dictionary<char, char> letters = new Dictionary<char, char>()
            {
                {'\u0041', '\uff21'},
                {'\u0042', '\uff22'},
                {'\u0043', '\uff23'},
                {'\u0044', '\uff24'},
                {'\u0045', '\uff25'},
                {'\u0046', '\uff26'},
                {'\u0047', '\uff27'},
                {'\u0048', '\uff28'},
                {'\u0049', '\uff29'},
                {'\u004a', '\uff2a'},
                {'\u004b', '\uff2b'},
                {'\u004c', '\uff2c'},
                {'\u004d', '\uff2d'},
                {'\u004e', '\uff2e'},
                {'\u004f', '\uff2f'},
                {'\u0050', '\uff30'},
                {'\u0051', '\uff31'},
                {'\u0052', '\uff32'},
                {'\u0053', '\uff33'},
                {'\u0054', '\uff34'},
                {'\u0055', '\uff35'},
                {'\u0056', '\uff36'},
                {'\u0057', '\uff37'},
                {'\u0058', '\uff38'},
                {'\u0059', '\uff39'},
                {'\u005a', '\uff3a'},
                {'\u0061', '\uff41'},
                {'\u0062', '\uff42'},
                {'\u0063', '\uff43'},
                {'\u0064', '\uff44'},
                {'\u0065', '\uff45'},
                {'\u0066', '\uff46'},
                {'\u0067', '\uff47'},
                {'\u0068', '\uff48'},
                {'\u0069', '\uff49'},
                {'\u006a', '\uff4a'},
                {'\u006b', '\uff4b'},
                {'\u006c', '\uff4c'},
                {'\u006d', '\uff4d'},
                {'\u006e', '\uff4e'},
                {'\u006f', '\uff4f'},
                {'\u0070', '\uff50'},
                {'\u0071', '\uff51'},
                {'\u0072', '\uff52'},
                {'\u0073', '\uff53'},
                {'\u0074', '\uff54'},
                {'\u0075', '\uff55'},
                {'\u0076', '\uff56'},
                {'\u0077', '\uff57'},
                {'\u0078', '\uff58'},
                {'\u0079', '\uff59'},
                {'\u007a', '\uff5a'}
            };
        

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            textBox2.Text = convertToFullwidth(textBox1.Text);
        }

        private string convertToFullwidth(string text)
        {
            string output = "";

            for (var i = 0; i < text.Length; i++)
            {
                char normal = text[i];
                try
                {
                    char latin = letters[normal];
                    output += latin;
                }
                catch (KeyNotFoundException e)
                {
                    output += normal;
                }
            }

            return output;
        }
    }
}

private static string getWide(string input)
{
    return input.Aggregate("", (current, c) => current + (c > 32 ? ("&#xff" + ((byte) (c - 32)).ToString("X2") + ";") : c + ""));
}