Comparing Text with a lot of If/else

I have variables which search specific words between two words

> string number207 = FindTextBetweenWithout(fileTTT, "\n207 ", " 20");
> string number208 = FindTextBetweenWithout(fileTTT, "\n208 ", " 20");
> string number209 = FindTextBetweenWithout(fileTTT, "\n209 ", " 20");
> string number219 = FindTextBetweenWithout(fileTTT, "\n219 ", " 20"); 

After i have a text file which contain numbers:

>207
>208
>209
>1402
>132

This numbers read with this method

 var listChrt = File.ReadAllText(textBox2.Text); 

So after i tried to compare this numbers

        string compare()
        {
            if (listChrt.Contains("207"))
            {
                return number207;        
            }
            if (listChrt.Contains("208"))
                {
                return number208;
            }
            if (listChrt.Contains("1402"))
             {
                return number1402;
             } 

            return " ";
        }

and i tried pass it into TextBox

 richTextBox1.Text = (
              dss()
                   );

But only get first return line which is number207.

As i undestood if else statement ends when it find true, but i need something to iterate through all my text file and find compares to my existed varibles(string number207,208 etc)