 For example, Keynes believed European output in iron would decrease but by 1929 iron output in Europe was up 10% from the 1913 figure.Keynes predicted that German iron and steel output would decrease but by 1927 steel output increased by 30% and iron output increased by 38% from 1913 (within the pre-war borders).Keynes also argued that German coal mining efficiency would decrease but labour efficiency by 1929 had increased on the 1913 figure by 30%.