"Neither a borrower nor a lender be," wrote Shakespeare in "Hamlet". Actually, the availability of debt, and the willingness to take it on, is a crucial ingredient of economic growth, because it allows individuals, firms and governments to make investments they would not otherwise be able to afford. The price of debt is interest. Until recently, lending was an activity dominated by banks (although mortgages for individuals buying their homes have long been available from special housing savings institutions). Since the 1960s, debt has become increasingly available from other sources. Companies have sold trillions of dollars worth of bonds to investors in the financial markets. Individuals have been able to borrow with credit cards, and for those who have nowhere else to turn there are pawn shops and loan sharks, which charge very high rates of interest. Total private-sector debt in 2003 was around 150% of GDP in the United States, compared with less than 100% in 1928. In most countries, by far the biggest single borrower is the state, through the national debt.