Last time I had a breach on Mac (no antivirus) was never. Last time I had a breach on GNU/Linux (no antivirus) was never. The two Windows 7 machines I care for, both have antivirus running, and still viruses manage to sneak through, that's why I started installing two antivirus softwares. Still, it is a huge improvement over Vista and XP and more secure than Snow Leopard according to most experts, though in practice it is different.
Also 2% is a huge risk to take
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