America has long been the primary engine of the global econom, but increasingly China and the rest of Asia have become a second important engine of growth. By some measures(based on purchasing-power parity) China has accounted for a slightly bigger slice of global growth than America in recent years. For many economies, exports to China have given a bigger boost to growth over the past year than have exports to America. In the past 12 months, Chinas imports have risen by 40%, Americas by a paltry 2%. Japans exports to Greater China(also including Hong Kong and Taiwan) are now bigger than those to America.
If the overhang of consumer debt does eventually cause Americas recovery to sputter, then the world economy will be better off if Chinas economy remains robust. Aeroplanes are always safer with two engines than with one.

이해가 안되는 부분이 있어서요. 마지막 문단에 첫문장이 이해가 잘 안됩니다.
개인부채가 미국 경제 성장의 발목을 잡으면 왜 세계 경제가 더 좋아질 거라는 건지. 중국이 건재하면 끄떡없다라고 하려면 그냥 원급을 쓰면 될거 같은데.
그 문장 해석 좀 부탁드립니다. overhang도 좀 설명해주시고요.