Case C-511/11 P: Judgment of the Court (First Chamber) of 13 June 2013 — Versalis SpA, formerly Polimeri Europa SpA v European Commission (Appeals — Agreements, decisions and concerted practices — Market in butadiene rubber and styrene-butadiene rubber manufactured by emulsion polymerisation — Fixing price targets, sharing clients by non-aggression agreements and exchanging commercial information — Evidence — Attributability of unlawful conduct — Amount of the fine — Gravity and duration of the infringement — Aggravating circumstance — Repeated infringement)