Susceptibility to this volatility can be increased where governments choose to borrow heavily in foreign currency. Real exchange rate increases, through capital inflows or the "Dutch disease" can make this appear an attractive option by lowering the cost of interest payments on the foreign debt, and they may be considered more creditworthy due to the existence of natural resources. If the resource prices fall, however, the governments' capacity to meet debt repayments will be reduced. For example, many oil-rich countries like Nigeria and Venezuela saw rapid expansions of their debt burdens during the 1970s oil boom; however, when oil prices fell in the 1980s, bankers stopped lending to them and many of them fell into arrears, triggering penalty interest charges that made their debts grow even more. As Venezuelan oil minister and OPEC co-founder Juan Pablo Pérez Alfonzo presciently warned in 1976: "Ten years from now, twenty years from now, you will see, oil will bring us ruin... It is the devil's excrement."