(Reuters) - U.S. companies are finding it more difficult to grow their revenue now than at just about any time since the financial crisis.

Second-quarter revenue growth for companies in the Standard & Poor's 500 index .SPX is expected to be just 2.2 percent compared with an average 7.3 percent quarterly increase since the fourth quarter of 1998, according to Thomson Reuters data based on Wall Street analysts' forecasts. Take out the supercharged sales of Apple Inc (AAPL.O) and the picture is even weaker - with growth of only 1.9 percent for the current period.

The lowered expectations are a result of the euro zone crisis hurting demand from Europe, the impact of a slowdown in major developing economies such as China, Brazil and India, and recent signs of weakness in the United States.