How to match chars like %19?

this is my scenario: I extract data from a file and I have to control for each line if it matches a regex. This regex is write on a configuration xml file. Some of this lines contains the %19 () char and I'm not able to match this, cause the char  isn't valid in xml.

E.g If I don't write the regex in xml this one match my line

(?<Numeri>\d{0,3}(&#x19;){0,1}(\s*?\d\d\d)*,\d{2})

With which string I have to replace  in xml?