In 2011, the proportion of the population aged 3 and over in Scotland who reported they could speak, read, write or understand Scots was 38 per cent (1.9 million). For Scotland as a whole, 30 per cent (1.5 million) of the population aged 3 and over reported they were able to speak Scots.

You will find various PDF tables detailing this and other census figures at: http://www.scotlandscensus.gov.uk/