Boeing Co (BA.N) on Tuesday raised its forecast for China’s aircraft demand over the next 20 years despite a slowing economy and a tumbling stock market that have triggered a worldwide slide in equity and commodity prices. The U.S. plane maker expects China will purchase 6,330 aircraft over the next 20 years, a 5 percent rise from last year’s two-decade estimate. Boeing currently values the aircraft demand at $950 billion.