Fifty-two percent of the soil of Castilla–La Mancha is considered "dry". Agricultural activities have historically been based on the cultivation of wheat (37.0 percent), grapes (17.2 percent) and olives (6.6 percent). Castilla–La Mancha has some of the most extensive vineyards in Europe, nearly . The vineyards are predominantly, but by no means exclusively, in the west and southwest of La Mancha. In 2005 the region produced of grapes, constituting 53.4 percent of Spain's national production. After grapes, the next most important agricultural product is barley, , 25.0 percent of the national total.