"Ireland has the second highest percentage; as many as 10% of the Irish population has red, auburn, or strawberry blond hair."
http://en.wikipedia.org/wiki/Red_hair
Source: Hooton, Earnest A. (1940). "Stature, head form, and pigmentation of adult male Irish". American Journal of Physical Anthropology 26 (1): 229. doi:10.1002/ajpa.1330260131