How often do you wash your blanket?

Singapore
January 13, 2010 9:10am CST
How often do you wash your blanket? - Picture of a lady sleeping. Photo source: http://i.telegraph.co.uk/telegraph/multimedia/archive/00677/Woman-Sleeping_677646c.jpg .
You know, that piece of thingy you use to cover your body when you sleep. Some people call it a blanket... how often do you wash it? I know some people are outright gross (*looks around innocently*) and they only wash theirs once a year. Some do so every month or every week. Of course some broke the record by never attempting the act at all. So what about you? Do you ever wash your blanket? How often do you wash it? Once a year? Per month? Every week? You don't use a blanket? What?