mod_deflate is not working for php generated page

mod_deflate not working for php generated page. I have Apache v2.4.7 with php v5.5.9 on Ubuntu 14.04.5 (LTS). This module is working for static html pages and other files like CSS, js etc.

here is my php information http://www.hostnology.com/test.php

• Only content is deflated, if you use HEAD http verb, there is no content, so no need to deflate it
• You can set (or there is) parameter in httpd that activate deflate on some mime type. (no need to deflate jpeg for instance)
• if content type is small (like <1k) there no point to deflate (size almost same)