(22)Where no reliable credit spread can be derived from the default statistics, as in the case of exposures to sovereign debt, the fundamental spread for the calculation of the matching adjustment and the volatility adjustment should be equal to the portion of the long term average of the spread over the risk free interest rate set out in Article 77c(2)(b) and (c) of Directive 2009/138/EC. As regards exposures to Member States' central government and central banks, the asset class should capture the difference between individual Member States.