The US economy grew at a 5 per cent clip in the third quarter, its quickest pace in 11 years and the strongest sign yet that growth has decisively shifted into higher gear.Some of the strength appears to have been sustained, with other data on Tuesday showing consumer spending rising solidly in November, offsetting surprisingly weak durable goods orders.The reports further set the US economy apart from the rest of the world, where growth is sputtering or activity shrinking."Our economy is firing on most cylinders, whereas the global economy is...