The [report] evaluates 42 leading international and national oil and gas companies operating in 21 countries, based on the transparency of their reporting, particularly on payments made to governments for resource extraction rights. [companies surveyed: BG Group, BHP Billiton, BP, Chevron, China National Offshore Oil Corporation (CNOOC), China National Petroleum Corporation (CNPC), ConocoPhillips, Devon Energy, Eni, ExxonMobil, Gazprom, GEPetrol, Hess, INPEX, KazMunaiGaz (KMG), Kuwait Petroleum Corporation (KPC), Lukoil, Marathon Oil, National Iranian Oil Company, Nigerian National Petroleum Company (NNPC), Nexen, Oil and Natural Gas Corporation Ltd. (ONGC), Pertamina, PetroChina, Petrobras, Petro-Canada, Petróleos Méxicanos (Pemex), Petróleos de Venezuela (PDVSA), Petronas, Qatar Petroleum, Repsol YPF, Rosneft, Saudi Aramco, Shell, Sinopec, Société Nationale des Pétroles du Congo (SNPC), Sonangol, Sonatrach, StatoiHydro,Talisman Energy,Total, Woodside]