Ik gok <1 %.
Van het Ubuntu forum:
Q: Is viruses, trojans and malware a threat to a linux system as in Windows?
A: No, there's a very few viruses to linux and the way a Linux/unix is build up makes it difficult to do any serious damage to the system, in fact I've never heard from people who got their Linux/unix system infected.
Q: So why install a anti-virus application/program?
A: For an ordinary Linux Home user with only one OS system their's no need for Anti-virus, but people who's running network, server or dual booting with win OS this tool can be very handy to scan and delete viruses.
Q: I'm a home user only running Linux do I need it?
A: No, a firewall is way better as protection in that case.