private void YearlyData()
        {
           string filePath = @"rainfall.txt";
           string line;
 
           if (File.Exists( filePath ))
           {
                StreamReader file = null;
                try
                {
                   file = new StreamReader( filePath );
                   while ((line = file.ReadLine()) != null)
                    {
                        textBoxList.Text = line;
                   }
                }
                finally
                {
                   if (file != null)
                       file.Close();
                }
           }
           
        }