THE United States economy grew at an annual rate of 4.5 per cent in the fourth quarter of last year against four per cent during the previous quarter, according to the Commerce Department. The growth rate was in line with analysts' expectations. The Commerce Department said the economy grew at the rate of four per cent for the year, the most rapid pace of growth since 1984 when the economy grew at a rate of 6.2 per cent. In 1993, the US economy grew at the rate of 3.1 per cent. The strong fourth-quarter performance was driven by consumer spending, particularly on the purchase of durable goods, according to the Commerce Department.