In 1995, the European Commission's Green Paper on 'Fair and efficient pricing in transport' put forward the policy of charging transport users according to the costs they impose. These costs include costs on society due to marginal increases in congestion, accidents and pollution. The Green Paper noted that the rich spend more of their income on transport than the poor and therefore would be charged more. However, the document also noted that increased charges could cause relatively greater hardship for people on low incomes, and called for further investigation of the impact of cost-internalisation strategies on different groups of consumers. This would allow compensating policies to be designed to minimise the risk of people being excluded from mobility.