在1963年，底层90%的人口需要让其财富增加六倍后才能成为中间阶层的9.9 % ； 但到了2010年，从底层90%跳到中间阶层9.9 % ， 他们需要让财富增加25倍。
In 1963, the 90% would have had to increase their wealth sixfold to reach the level of the 9.9%; by the 2010s, they would need 25 times their wealth to reach that level.