Well obvisiouly we are talking about the past in this topic not present. Since we don't have any census of the present. There was a population census taken in Somalia somewhere in 1970's and it mentions Siad bare wasn't impressed with the outcome hence hiding it.
Isaaqs in Somaliland are about 2m - 2.5m.
Isaaqs in Ethiopia - 400,000 - 600,000.