Much of this rise stems from growing prosperity and current-account surpluses in middle-income countries. When you sell more to the world than you buy, you accumulate claims on the rest of the world – and you need to decide the form in which you want to hold those claims.
该比重的上升很大一部分来自中等收入国家的繁荣和经常项目盈余。当你向世界卖出的东西小于买进的东西时，你就会累积对世界其他部分的债权，并且你需要决定以何种形式持有这一债权。