Joe saves this same amount annually until age 70 and earns an average compound annual return over that time of 6% by investing in a balanced mix of low-cost stock and bond mutual funds.
Mr Thakkar, scrutineer of the Indian water scene, says that although the installed capacity of India's hydro projects increased at a compound rate of 4.4% a year between 1991 and 2005, the amount of energy generated actually fell.