Question: Which airport is a key component to 7th least corrupt economy in the world?
Sentence (from "Economy of Singapore"): Singapore's economy has been ranked as the most open in the world, 7th least corrupt, most pro-business, with low tax rates (14.2% of Gross Domestic Product, GDP) and has the third highest per-capita GDP in the world in terms of Purchasing Power Parity (PPP).
Relevant evidence: Yes