Wordpress Theme's footer.php file.

WP footer.php

<!-- footer -->
<footer class="l-footer">

  <!php wp_footer(); ?>
</footer><!-- end footer -->

<!-- Google Analytics: change UA-XXXXX-X to be your site's ID. -->
<script>
  var _gaq=[['_setAccount','UA-XXXXX-X'],['_trackPageview']];
  (function(d,t){var g=d.createElement(t),s=d.getElementsByTagName(t)[0];
  g.src=('https:'==location.protocol?'//ssl':'//www')+'.google-analytics.com/ga.js';
  s.parentNode.insertBefore(g,s)}(document,'script'));
</script>
</body>
</html>