The U.S. economy is expected to grow at its strongest pace in almost four years during the second half of the year, according to a Wall Street Journal survey of economists released today. Gross domestic product, the value of all goods and services produced, was expected to grow at a seasonally adjusted annual rate of 4.7% during the current quarter and 4.0% in the fourth quarter, the survey found. The growth rates taken together would be the fastest since the economy expanded at an annual pace of more than 6% in the second half of 1999. Economists said there is mounting evidence that consumer and business spending has accelerated, boosting economic growth, the Journal reported.