https://www.av-test.org You can find here test results done by AV specialists.
From their site: Protection against 0-day malware attacks, inclusive of web and e-mail threats (Real-World Testing) - industry average: 98%
Detection of widespread and prevalent malware discovered in the last 4 weeks (the AV-TEST reference set) - industry average: 100%
It's amazing that anyone gets infected, ever!
... 98% chance of blocking a zero-day attack. That's... impressive. It's also odd how zero-day attacks stir up a lot of press considering these anti-malware products are apparently almost completely bulletproof. There was a news article recently about how Google had partnered up with Adobe in order to help them improve the security of the Flash plug-in. Sure enough, a zero-day got through despite their efforts. Why didn't they team up with these anti-malware companies, who obviously know how to detect and block stuff that they've never even encountered before?
What's truly amazing is that anyone takes these people seriously.