Track 404 with google analytics

gistfile1.js

var _gaq=[['_setAccount','UA-XXXXX-X'],['_trackPageview', '/404?p=' + encodeURIComponent(document.location.pathname + document.location.search) + '&r=' + encodeURIComponent(document.referrer)]];
(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'));