However, previous experiences in other countries suggest that perhaps the overall anemic credit growth may mask some asymmetric sectoral pattern. As documented by Tornell and Westermann (2002), twin crises (concurrent occurrence of both exchange rate and banking crises) tend to be preceded by real exchange rate appreciation and a lending boom in which the ratio of credit to GDP grows unusually fast. Following the crises, there is typically a short-lived recession and a protracted slowdown in bank lending that persists long after aggregate growth has resumed. The credit crunch hits mainly small and non-tradables firms. In fact, non-tradables production declines relative to the output of the tradables sector for several years after the crisis, and the credit-to- GDP ratio falls.