The rise of the middle class

Every time I visit India, I am simply amazed at the sheer number of people who have transitioned into a middle class life.

(Though, it equally depresses me that there are millions who are "slumdogs")

So, reading the following in the Economist is not a surprise to me:

By the 1960s they comprised just under a third of the world's population. Nowadays the chance that you are a memeber yourself is high—57% of the globe count as middle class, according to Surjit Bhalla, an Indian economist.