Joined Cases T-55/06 and T-66/06: Judgment of the General Court of 16 November 2011 — RKW and JM Gesellschaft für industrielle Beteiligungen v Commission (Competition — Agreements, decisions and concerted practices — Plastic industrial bags sector — Decision finding an infringement of Article 81 EC — Fines — Guidelines for the calculation of fines — Maximum limit of 10 % of turnover — Implementation — Legality — Proportionality — Equal treatment — Single and continuous infringement — Attenuating circumstances — Exclusively passive role — Obligation to state the reasons on which the decision is based — Imputability of unlawful conduct)