[NTG-context] %18 or 18% : incorrect placement of the percentage sign ?

Hi, I have often seen (in arabic newpapers) the percentage sign set left to the number "% 18". Recently I read an article (http://sehstoerung.sonance.net/pdfs/ TitusNemeth_dissertation.pdf) that calls this "... the incorrect placement of the percentage sign". Any native arabic speaker out there? Is it %18 or 18% ?? Thanks, Steffen