Why the Pacific Counts in One Graphic

I quote from the article in The Economist:

Since the 1970s trade across the Pacific has far outrun the Atlantic sort. China, for instance, has taken its hunger for high-protein food and raw materials to Latin America and become the biggest trading partner of distant Chile. By one estimate, in 2010 it promised more loans to Latin America than the World Bank, the Inter-American Development Bank and the United States Export-Import Bank combined.