(12)Member States’ obligations to guarantee insurance cover at least in respect of certain minimum amounts constitute an important element in ensuring the protection of victims. The minimum amount of cover for personal injury should be calculated so as to compensate fully and fairly all victims who have suffered very serious injuries, while taking into account the low frequency of accidents involving several victims and the small number of accidents in which several victims suffer very serious injuries in the course of one and the same event. A minimum amount of cover per victim or per claim should be provided for. With a view to facilitating the introduction of these minimum amounts, a transitional period should be established. However, a period shorter than the transitional period should be provided for, in which Member States should increase these amounts to at least half the levels provided for.