The spelling of the word "kuhn" is unusual and confusing. It is pronounced as /ku:n/, with a long "u" sound and a silent "h". The reason for this spelling is that the word comes from a German surname, and the original German spelling was Kühn. However, the umlaut (the two dots above the letter "u" in German) is not used in English, so the spelling was adjusted to "kuhn". This is an example of how language and spelling can evolve and change over time.
* The statistics data for these misspellings percentages are collected from over 15,411,110 spell check sessions on www.spellchecker.net from Jan 2010 - Jun 2012.