5. Oil And Gas Exploration & Production
Revenue: $3,325 billion
The main duty of this industry as the name implies is the extraction of natural and crude oil from various reserves in the world. With global oil rates fluctuating at a steady pace, this industry has experienced a slight increase in the last couple of months and so have made this list.
While most experts in this industry predict a decline in global oil prices in the months or years to come, this industry has managed to remain on this list because of its current revenue.