D'imperio Paolo Department of the Treasury - Italian Ministry of Economy and Finance   via XX Settembre, 97 Rome, RM 00187 Italy   paolo.dimperio@mef.gov.it             JEL Areas: E3 : Prices, Business Fluctuations, and Cycles: General (includes Measurement and Data) E6 : Macroeconomic Policy, Macroeconomic Aspects of Public Finance, and General