About three per cent of mainland Norway is cultivated as compared with 11 per cent for the world as a whole. Some of the land resources available for agriculture are not in use, either temporarily or on a permanent basis. Agricultural areas that are permanently abandoned generally become overgrown with forest. The last national statistics based on the detailed land resource survey of agricultural areas was completed in 2006, when the total agricultural area was 10903 km2 and the undeveloped reserve was 12342 km2. The last agricultural survey – completed in 1989 – also showed that 7.4 per cent of the land developed for agriculture was currently not in use.