Norn was also spoken at one point in Caithness, apparently dying out much earlier than Shetland and Orkney. However, the Norse speaking population were entirely assimilated by the Gaelic speaking population in the Western Isles; to what degree this happened in Caithness is a matter of controversy, although Gaelic was spoken in parts of the county until the 20th century. Diagrammatic representation of the development of the historic Indo-European languages of Scotland:  According to the 2001 census Scottish Gaelic has 58,652 speakers (roughly 1% of the population of Scotland). In total 92,400 people aged three and over in Scotland had some Gaelic language ability in 2001. 15,723 of these reside in the Outer Hebrides, where the language is spoken by the majority of the population. There are also large populations of speaker in other parts of the Highlands. A Scottish Government study in 2010 found out that 85% of Scotland's adult population speak Scots. However, according to the 2011 census, 1,541,693 people can speak Scots in Scotland, approximately only 30% of the population.