The opening of Panama Canal in 1914 caused a severe drop in traffic along Chilean ports due to shifts in the maritime trade routes. In addition to this international trade collapsed and state income was reduced to half of its previous value after the start of the World War I in 1914. The Haber process, first applied on an industrial scale in 1913 and later used as part of Germany's war effort due to its lack of access to Chilean saltpetre, ended Chile's monopoly on nitrate and led to an economic decline in Chile. While saltpetre mining gradually waned in importance copper mining rose, exporting raw materials to a level unprecedented in the history of Chile. By 1929 copper exports had reached the same values as saltpetre exports, and in 1937 the value of copper exports largely surpassed that of saltpetre. In the 1920–1937 period both industries had combined a 70–83% share of the value of Chilean exports.