The following chart shows the number of Cruickshank(s), Cruikshank(s), Crookshank(s), etc., born in Scotland as registered in the Old Parish Registers (1553-1854), and Statutory Registers (1855-2006). Results were obtained by performing a search of both Registers using "Cruickshank" with 'Soundex' ON as the variable. All numbers are approximate and are published as a reference to the demographic movements of those bearing a Cruickshanks variant surname.

Note the shift of population in the last 150 years from the North Eastern regions where over 80% of the births were prior to 1855, to the South Western areas (65% post 1855), most likely due to the Industrial Revolution and employment opportunities. I imagine that other surnames would follow a similar pattern.