How potent is Plan B at preventing pregnancy?

I was only curious to know how effective the Plan B pill is at preventing pregnancies. My fiancé and I hang on to it on hand contained by case one of our condoms breaks accidently. Way better than nought in an emergency, but even the entrepreneur doesn't claim a 90% effectiveness rate. Their own website and bundle literature says it "works for seven out of eight women". So for every seven satisfied women, there's one really unhappy one.
You're at most minuscule using it correctly, for its intended purpose. I knew when this stuff become available over-the-counter that there be going to be those who use it incorrectly, without even reading the directions. If you read seriously of the questions surrounded by the section, you'll see that plentiful people judge it's a Magic Pill that will allow them to have sex short a condom whenever they feel resembling it. Or that it protects them for a whole month (it doesn't). Or that it's of late as effective after 72 hours as it is inwardly the first 24 (and it most definitely isn't).
It's in reality become the birth control method of choice for some married couples. Makes me want to bang my cranium against the wall.
75 percent plus... having it on foot is a great idea