I've seen before though that "when used properly" condoms are over 98% effective. Lots of guys just fail at them. They are strong as fuck, the breakage occurs almost exclusively from improper use. Like not leaving room in the tip or not rolling it down all the way or putting it on backwards or worst of all trying to use it without enough or the wrong kind of lubrication. Also "double bagging" is actually worse and makes the breakage chance higher, if some people are actually dense enough to do that shit.
Planned Parenthood - Condoms
Don't see their source for the stats, but seems to match up with the CDC's 18% number.