Beer in the United Kingdom has a long history, and has quite distinct traditions. Historically the main styles were top-fermented Bitters, Porters, Stouts and Milds, but after World War II lagers took over half the market by volume. The Campaign for Real Ale (CAMRA) was founded in 1971 and has encouraged the preservation and revival of traditional styles of ale. In particular CAMRA has promoted cask conditioned beer, which completes its maturation in casks in the cellar of the pub rather than at the brewery. As of 2014[update] the UK drank 634 million imperial pints (360 million litres) of cask ale, representing 60% of ale in pubs and restaurants and 17% of all beer in pubs.[2] In total 42.42 million hectolitres of beer were produced in 2013[3] of which 48% was sold in the off-trade (retail shops).[4]