I just found this on Wikipedia, so you can believe as much of it as you want, but it's some interesting numbers.

Total population of Scotland
6–8 milllion
Ancestral Diaspora
est. 28–40 milliona[1][2]

Regions with significant populations
Scotland 4,459,071 (2001)
(Scottish descent only) [3]
United States 9,365,490b [4][5]
Canada 4,719,850 [4]
Australia 1,501,204 [6]
Englandc 795,000
Argentina 100,000 [7]
Chile 80,000 [8]
New Zealandd 12,792 [9]
Isle of Man 2403 [10]