It was first held in Oslo, Norway, in 2008, with only three competitors, but grew in popularity each year after. The 2018 competition attracted 3,157 competitors from 61 countries. The 2020 championship was cancelled due to the COVID-19 pandemic. The championship resumed in 2021, with both in-person events and a new online format, in which competitors create and submit their recipe remotely. Operation Traditional According to the instructions, fine-ground coffee is placed in the bottom of the larger cylinder on top of a paper microfilter. Hot water at approximately for dark roast coffee or for lighter roast is then poured over the coffee; this mixture is stirred for approximately 10 seconds before being forced through the microfilter by pushing the plunger downwards. In the different coffee competitions worldwide (World Barista Championship, Brewers Cup), the coffee is more often ground slightly finer than 'filter grind', and the dose is between , with about of water at and a steeping time of 30 to 60 seconds. Inverted Baristas and coffee drinkers have also developed methods of brewing using the AeroPress with an inverted brewing technique. In inverted brewing, the plunger is placed into the column from the beginning, close to the "top" of the column, and the entire AeroPress stands upside-down, resting on the top of the plunger. One or two scoops of ground coffee are added, followed by water, and the entire mixture then stirred. While that brews, a filter is placed into the filter cap and moistened to help it stick in place then the AeroPress cap is placed on top of the column and screwed into place. Lastly, once the desired brewing time is complete the AeroPress is either turned right-side-up and plunged normally or held at an angle and plunged horizontally. This method is more similar to the French press, particularly the extended brewing time in which the grounds and water sit together. This makes it useful for using grinds that wouldn't be optimal in the official method such as coarse grinds that might be used in a French press. Traditional method coffee properties Claimed to have roughly the same concentration as espresso Higher pH (thus lower acidity) than drip coffee 30-second total brewing time Contrasts with other immersion brewing methods The AeroPress uses finely ground bean, has a short brewing time of 30 seconds and, similar to espresso, uses pressure to extract flavor. French press (cafetière) uses