40. A crop's share in the sub-region's total arable area demonstrates not only a crop's natural suitability but also the prevailing farming knowledge and practices. This indicator roughly shows the degree of a crop's distribution across sub-regions and countries. Annual/permanent crops with a harvested area above five percent of a sub-region's total arable area were retained as the naturally suitable sub-regional crops. Annual/permanent crops representing less than five percent of the sub-region's arable area but covering over five percent of a country's arable area were retained as naturally suitable country-specific crops (Annexes 2-7). However, the crop pattern does not entirely disclose the fullness of the comparative advantage for a given crop. Therefore, the selection of potentially competitive crops was based on their production and trade potential.