Therefore, for each element the risk assessment score is multiplied, dependent on the category, by the relative share in primary energy sources (PES), final energy demand (FED) or total energy import. Adding the individual values together and multiplying the total by 100/48 results in the risk assessment sub-index (a value between 0 and 100). This is partly due to international commitments such as the IEA Treaty and partly due to national contingency planning.