While business activity is expected to pick up in 2011, weak sales remain the biggest worry for companies, according to a new survey by the Federal Reserve Bank of Philadelphia. Temple economist William Dunkelberg tied the weak sales environment to an increase in the national savings rate from 1 percent before the recession to about 6 percent now. Each percentage point of the savings rate is equivalent to about $100 billion in consumer spending. In essence, he said, consumers have removed $500 billion in spending from the economy.