What percentage of soy is fed to ‘livestock’ in the UK?

One of the criticisms of a vegan or vegetarian diet you see cropping up, again and again, is that it is actually responsible for large amounts of deforestation because it encourages people to consume more food products made from soy. Drink soy milk? Eat tofu or soy-based meat substitutes? Then is the destruction of the Amazon really on your hands?!