US researchers from the Society for Microbiology and The Soap and Detergent Association have worked out that only 77% of Americans wash their hands in public restrooms (loos to the rest of us).
(This figure is down 6% on a similar study in 2005. So this is for the Americans: When washing your hands you should rub your wet, soapy hands together outside the stream of running water for at least 20 seconds, before rinsing thoroughly and then drying with a clean or disposable towel. In a public loo, after drying, use a dry paper towel to turn off the water (and open the door, if there is one).