There is an old joke about corruption in Africa.
Why has Asia boomed in recent decades, while Africa has sunk into penury?
The pithiest answer is a joke I first heard in Nigeria. An African and an Asian make friends at Oxford before becoming politicians.
Years later, the African visits the Asian and is impressed by his mansion, with a Mercedes-Benz in the drive.
"How can you afford this?" he asks. The Asian points to a majestic highway outside. "See that road?" he says with a wink. "Ten per cent."
Later the Asian visits the African's home - a palace with a dozen Mercedes-Benzes.
Anticipating the question, the African says: "See that road?" The Asian sees only bush. "100 per cent."