The excel file TD7_PPP provides Consumer Price Indices and Nominal Exchange Rates with the US\$ for 23 industrialized countries in 1973 and 1993. Nominal exchange rates are expressed in terms of the currency of the country per US\$. Compute for each country: - the difference in log- of the nominal exchange rate between 1973 and 1993 (rate of depreciation of the currency). - the difference in log- of the consumer price indices between 1973 and 1993 (inflation rate), and the corresponding inflation differential relative to the US (in log-)