A third and final official estimate has shown that the US economy suffered its worst performance for five years in the first quarter of 2014. The US Commerce Department said the economy shrank by an annualised rate of 2.9 per cent. It was almost double economists' expectations for a fall of 1.7 per cent. A second estimate last month showed the economy shrank by one per cent, blaming the unusually cold winter for the fall. The gap between the second and third estimates is the largest on record. Growth in the US economy has now been revised down by 3 per cent since the first estimate.