9. Buenos Aires, Argentina

A metro ride in the capital city of Argentina costs daily commuters of the city a 2 percent of their household income.

8. Kiev, Ukraine

Kiev residents have to spend 3 percent of their earnings to travel in a metro in the city annually.

7. Cairo, Egypt

At the 7th spot is Egypt's capital Cairo where residents shell out 4 percent of their income on metro travel.

5. Mexico City and Jakarta

The fifth spot is shared by the country capitals of Mexico and Indonesia where the metro costs residents 6 percent of their incomes.

4. Mumbai

The financial capital of India does not have a fully developed metro network to all the parts of the cities and still costs its residents 8 percent of their household incomes.

3. Manila, Philippines

Eating up 12 percent of the citizens' annual incomes, the metro ride in Manila is the third most unaffordable in the world.

2. Delhi

After nine years of operation, the Delhi Metro fares were raised in 2017 as suggested by the Fourth Fare Fixation Committee and not the Delhi Metro Rail Corporation considering the input costs of expansion and revenues.

The study said that 30 percent of the metro commuters in the city have an average income of Rs 20,000, which meant they spent 19.5 percent of their income on travel. It also highlighted that Delhi metro ridership fell by a sharp 46 percent after the fare hike.

1. Hanoi, Vietnam

Eating up a major 25 percent of an average resident's income, the Vietnamese capital is the most unaffordable in the world according to the CSE Study.