The figures are based on different primary data covering the period from the end of the 1980s to the middle of the 1990s. The Primary data are arealanvendelseskortet; Areal Information System, (The Ministry of Environment). The figures are a revision (not an update) of the collected data. The National Environmental Research Institute has done the revision in 2001. The classification is based on the 3. digit CORINE land cover nomenclature, as a 4'th. number is added for national