How important is the U.S. market for China?

From the BBC World Service: Trade tensions are flaring as Beijing responds to President Donald Trump’s threats to tack an additional 100% tariff on Chinese goods. China has warned of "corresponding measures," though new data shows that China’s exports are booming. So does China still need the U.S.? Then, Nigeria produces nearly 40% of the world's shea nuts, which sustains a multibillion-dollar trade in cosmetics, food, and medicine. But new trade restrictions are being felt throughout the shea nut supply chain.