vdd
not totally sure, I think it is more like 30-40% who are official language speakers (ie they have the appropriate language badge and make public announcments on board). There are numerous others who aren't level four fluency or higher but therefore applied as a non-language speaker because they didn't have the certificate to show at registration. (stage 1 of interviews).
I'd say this is why the imminent recruitment is for speakers only, because they are looking to top up numbers. (i've also heard Japanese speakers are in demand more than the Chinese languages, but they definitely want both.)