Extension download links should have rel="nofollow" or be excluded via robots.txt
As it is now, they are followed by crawlers thus downloads are counted even though most web crawlers are really not interested in .zip.
Some background: https://support.google.com/webmasters/answer/96569?hl=de
The advice from here would be to add a robots.txt for internal links that should not be followed. Or (does not hurt and is very explicit IMHO) add rel="nofollow" to the download link.