Many emerging countries still aspire to the double-digit growth rates experienced from the mid-1960s to the early 1990s, when populations and trade were booming. But no economy had grown so fast before then, and as population and trade surges recede, it’s unlikely any country can repeat those feats.

As growth downshifts, even little miracles are disappearing. The benchmark for rapid growth should come down to 5 percent for emerging countries, to between and 3 and 4 percent for middle-income countries like China, and to between 1 and 2 percent for developed economies like the United States, Germany and Japan.