Question: The Sleaford, England brewery founded in 1777, now owned by The Bass Maltings, had an annual output of how many barrels by 1877?

Context paragraphs:
Bass Maltings, Sleaford: The Bass Maltings in Sleaford, England are a large group of eight disused malt houses originally owned by the Bass Brewery of Burton upon Trent.  Constructed between 1901 and 1907 to Herbert A. Couchman's design, the maltings are the largest group of malt houses in England; they have been designated Grade II* on the National Heritage List for England, recognising them as "particularly important ... of more than special interest."

Christian Heurich Brewing Company: The Christian Heurich Brewing Company was a Washington, D.C., brewery founded in 1872 and incorporated by Christian Heurich in 1890.  First located near Dupont Circle on 20th Street NW, it expanded to a much larger site in Foggy Bottom in 1895 after a major fire.  The new brewery was located along the Potomac River at 26th and D streets where the John F. Kennedy Center for the Performing Arts now stands.  The Heurich brewery was the largest in Washington's history, capable of producing 500,000 barrels of beer a year and 250 tons of ice daily.

Natural resource and waste management in Tanzania: Tanzania, officially known as the United Republic of Tanzania, is a mid-sized country in southeastern Africa bordering the Indian Ocean.  It is home to a population of about 43.1 million people.  Since gaining its independence from the United Kingdom in 1961, Tanzania has been continuously developing in terms of its economy and modern industry.  However, the country’s economic success has been limited.  Environmental obstacles, such as the mismanagement of natural resources and industrial waste, have been contributing factors and results of the relatively low economic status of the country.  Tanzania’s annual output still falls below the average world GDP.  In 2010, the GDP for Tanzania was US $23.3 billion and the GDP per capita was US $1,515.  Comparatively, the GDP for the United States was $15.1 trillion and the GDP per capita was approximately $47,153.  Eighty percent of the workers accounting for this annual output in Tanzania work in agriculture, while the remaining 20% work in industry, commerce, and government organizations.  Such a heavy reliance on agriculture has placed a huge amount of strain on an already limited supply of viable land.

Klosterbräu Bamberg: Klosterbräu Bamberg is the oldest brewery in Bamberg, Upper Franconia, Germany.  It is located in the so-called "Mühlenviertel" near the river Regnitz.  The annual output is about 4,000 hectoliters.

Marble Brewery (Albuquerque, New Mexico): Marble Brewery is a brewery in Albuquerque, New Mexico, founded in 2008.  As of 2014, it was the second largest brewery in New Mexico behind Santa Fe Brewing Company with an annual production volume of 13,000 US barrels.  In 2016, the brewery completed a major expansion which increased the production capacity to 30,000 barrels.  Its beers have won several awards and it was named Small Brewery and Brewmaster of the Year at the 2014 Great American Beer Festival.

Shepherd Neame Brewery: Shepherd Neame is an English independent regional brewery founded in 1698 in Faversham, Kent, and family-owned since 1864.  The brewery produces a range of cask ales and filtered beers. Production is around 210,000 brewers' barrels a year.  It owns 328 pubs and hotels, predominantly in Kent, London and South East England.  The company exports to more than 35 countries including Sweden, Italy, Brazil and Canada.

Calasparra Photovoltaic Power Plant: Calasparra Photovoltaic Power Plant (Spanish: "Planta solar fotovoltaico Calasparra" ) is a photovoltaic power station in Calasparra, Murcia in Spain.  The project consists of different production units.  Calasparra II is a 6.67 MW ground-mounted unit with estimated annual output of 11.82 GWh.  Calasparra III is a 6.6 MW units with estimated annual output of 11.7 GWh.  The project was developed by FRV and constructed by Gestamp Solar.

Burley Hydro: Burley Hydro Scheme also known as Greenholme Mill Hydro is a micro hydroelectric scheme installed on the River Wharfe at Burley-in-Wharfedale, West Yorkshire, England.  The power output of the hydro scheme is 330 kWh with an annual output of 1,400 MWh and is the fourth hydro scheme on the river after the opening of similar power plants at Linton near Grassington, and two further downstream from Burley at Pool-in-Wharfedale and Garnett Wharfe at Otley.  All of these schemes have been located on sites previously used to generate power from the water flow.

Adnams Brewery: Adnams is a regional brewery founded in 1872 in Southwold, Suffolk, England, by George and Ernest Adnams.  It produces cask ale and pasteurised bottled beers.  Annual production is around 85,000 barrels.

Bass Brewery: The Bass Brewery was founded in 1777 by William Bass in Burton-upon-Trent, England.  The main brand was Bass Pale Ale, once the highest-selling beer in the UK.  By 1877, Bass had become the largest brewery in the world, with an annual output of one million barrels.  Its pale ale was exported throughout the British Empire, and the company's distinctive red triangle became the UK's first registered trademark.

Supporting paragraphs: Bass Maltings, Sleaford Bass Brewery
Answer: one million