"Red hair and blue eyes is the rarest combination on the planet
While less than four percent of the world’s population have red hair (Scotland is the highest, at around ten percent), most of these have brown eyes. As both red hair and blue eyes are recessive genes, finding the two in combination is about as common as finding a four-leaf clover. Red hair and blue eyes occurs in less than one percent of the world population."

http://www.only-apartments.com/news/redheads/