4. Member States shall put in place the restoration measures that are necessary to re-establish the habitat types listed in Annex I in areas where those habitat types do not occur, with the aim of reaching the favourable reference area for those habitat types. Such measures shall be in place on areas representing at least 30 % of the additional surface needed to reach the total favourable reference area for each group of habitat types listed in Annex I, as quantified in the national restoration plan referred to in Article 15, by 2030, on areas representing at least 60 % of that surface by 2040, and on 100 % of that surface by 2050.