Have you ever wondered how many people wash their hands thoroughly after using the restroom? You may be shocked by the actual number.

Researchers at Michigan State University recently observed nearly 4,000 bathroom visitors. The result: 95 percent of people DID NOT wash their hands thoroughly enough to kill germs. And it got worse: 1 in 3 hand-washers didn’t use soap. And 1 in 10 people didn't wash their hands at all.

The CDC says that germ-free hands are absolutely the best way to curb the spread of infectious diseases. They also say that poor hand-washing causes nearly half of all foodborne illness outbreaks, by spreading E.coli from bathroom germs onto food.

If you want germ-free hands, the experts say you have to spend 15 to 20 seconds vigorously washing with soap and water. That's about how long it takes to sing Happy Birthday twice. But researchers found that the average person spends only 6 seconds washing up. Which isn’t nearly enough.

Other facts: Men are twice as likely to skip hand washing as women and men who wash up are half as likely to use soap.

Interestingly enough, according to the study, bathroom visitors are less likely to wash their hands if the sink is dirty. And the later in the day it is, the less likely people are to wash their hands, period. The researchers believe it’s because people who are out for dinner or drinks feel relaxed, so hand washing is less important.

The good news: People were more likely to wash their hands if there was a sign posted in the bathroom encouraging hand-washing.

Just something to think about next time you shake somebody’s hand.