reducing duplication in static HTML pages

<html>
  <head></head>
  <body>
    <h1>My Common Header</h1>
  </body>
</html>

<h1>My Common Header</h1>

<h1>My Common Header</h1>

<html>
  <head></head>
  <body>
    <?php include('header.php'); ?>
  </body>
</html>

<!--#include virtual="file.inc"-->

<html>
<head></head>
    <body>
        <? include 'header.php'; ?>
    </body>
</html>

<h1>My Common Header</h1>