Question: The Silverdome refers to the stadium that opened in what year?

Context paragraphs:
Hangar (Lancaster, California): The Hangar, formerly known as Lancaster Municipal Stadium and Clear Channel Stadium, is a stadium in Lancaster, California.  It is built just off California State Route 14.  It is primarily used for baseball, and is the home field of the Lancaster JetHawks minor league baseball team of the California League.  It was built in 1996 and was known as the Lancaster Municipal Stadium.  In 2005, Clear Channel Communications entered into a 10-year, $770,000 naming rights deal with the JetHawks and the City of Lancaster.  The City of Lancaster and the JetHawks will divide the revenue from the deal equally.  The deal runs through the 2014 season.  However, the signage stating Clear Channel Stadium was removed during the 2012 season and the stadium is now known as The Hangar, its nickname since the stadium opened in 1996.

Silverdome (disambiguation): Silverdome most often refers to the Pontiac Silverdome, an American stadium formerly home to the Detroit Lions and Pistons.  It may also refer to:

Georgia World Congress Center: The Georgia World Congress Center (GWCC) is a convention center in Atlanta, Georgia, USA.  Enclosing some 3.9 million ft (360,000 m) in exhibition space and hosting more than a million visitors each year, the GWCC is the third-largest convention center in the United States.  Opened in 1976, the GWCC was the first state-owned convention center established in the United States.  The center is operated on behalf of the state by the Georgia World Congress Center Authority, which was chartered in 1971 by Georgia General Assembly to develop an international trade and exhibition center in Atlanta.  The authority later developed the Georgia Dome, Centennial Olympic Park, and Mercedes-Benz Stadium, which replaced the Georgia Dome.  The Georgia Dome was closed on March 5, 2017 and is scheduled for implosion on November 20, 2017 while Mercedes-Benz Stadium officially opened on August 26, 2017.  While the GWCCA owns Mercedes-Benz Stadium, AMB Group, the parent organization for the National Football League's Atlanta Falcons and Major League Soccer's Atlanta United FC, is responsible for the stadium's operations.

Michigan Competing Band Association: The Michigan Competing Band Association (MCBA) is a sanctioning body for high school marching band field contests in the state of Michigan, established in 1974.  Not only does it host a great number of local competitions around the state, MCBA holds the only statewide marching band championships in Michigan.  Previous championships were held at the Plymouth-Canton Educational Park Varsity Stadium in Canton, Michigan, Rynearson Stadium at Eastern Michigan University, and at the Pontiac Silverdome in Pontiac, Michigan.  They are currently held at Ford Field in Detroit, Michigan.  Prior to the 1992-93 school year, MCBA was known as the Michigan Competing Band Director's Association, or MCBDA.

Children's Mercy Park: Children's Mercy Park (formerly Sporting Park and Livestrong Sporting Park) is a soccer-specific stadium in Kansas City, Kansas, United States, and is the home of Sporting Kansas City.  The stadium is located near Kansas Speedway and it opened during the 2011 season of Major League Soccer on June 9, 2011 with a match against the Chicago Fire.  The stadium has a seating capacity of 18,467 seats, which can expand to 25,000 for concerts.  Most SKC games attract around 21,000 because of different stadium modes.  The stadium is Sporting Kansas City's third home venue; then known as the Kansas City Wizards, the team played in Arrowhead Stadium from 1996 to 2007 and CommunityAmerica Ballpark from 2008 to 2010.  In 2013, the stadium hosted the MLS All-Star Game, the United States men's national soccer team, and the MLS Cup, three of the most prestigious matches in the United States, and is the only stadium to host all three in the same year.

National Heroes Stadium: Heroes National Stadium is a multi-purpose stadium in Lusaka, Lusaka Province, Zambia.  It is currently used mostly for football matches and hosts the home matches of the Zambia national football team.  The stadium holds 60,000 spectators.  It opened in 2014.  The name of the stadium refers to the 1993 Zambia national football team air disaster which took the lives of most of its national football team.

Bloomfield Road: Bloomfield Road is a 17,338-capacity all-seater football stadium in the English town of Blackpool, Lancashire, in an area known as South Shore.  It has been the permanent home of Blackpool F.C. since 1901, and was the 68th ground to host a Football League game.  The stadium is named after the road on which the main entrance used to stand.  The stadium has been in a process of redevelopment since 2000.  June of that year saw the demolition of the Spion Kop at the north end of the ground; an all-seated stand has now replaced it.  The rebuilding of the West Stand was completed in August 2002.  In March 2010, the South Stand, whose original structure was pulled down in 2003, was opened by Jimmy Armfield, the former Blackpool player for whom the stand is named.  A temporary East Stand opened on 28 August 2010 with a capacity of 5,120 seats, initially increasing capacity to 16,220 with further hospitality seating in the South Stand to be installed later in the year.  Bloomfield Road is ranked 52 in the list of English football stadiums by capacity.

IAI Stadium Nihondaira: The IAI Stadium Nihondaira (IAIスタジアム日本平, pronounced as "I-A-I") is a football stadium in Shimizu-ku, Shizuoka, Japan.  It is currently mostly used for football matches and has been the home stadium of the J-League's Shimizu S-Pulse since 1993.  The stadium holds 20,339 people and was opened in 1991.  In November 2008 a four-year naming deal effective from March 2009 was announced expected to earn S-Pulse 360,000,000 yen.  The stadium was known as The Outsourcing Stadium until February 2013.  As Shizuoka City and Shimizu S-Pulse reached a 5-year deal with IAI Corporation, a manufacturer industrial robots, the stadium has been renamed as IAI Stadium Nihondaira effective 1 March 2013.

Pontiac Silverdome: The Pontiac Silverdome, formerly known as the Silverdome, is a stadium in Pontiac, Michigan, United States, which is a suburb of Detroit.  It opened in 1975 and sits on 127 acre of land.  When the stadium opened, it featured a fiberglass fabric roof held up by air pressure, the first use of the technique in a major athletic facility.  The roof has since been destroyed.  With a seating capacity of 82,000, it was the largest stadium in the National Football League (NFL) until FedExField (91,000 capacity) in suburban Washington, D.C., opened in 1997.

Estadio Nacional de Costa Rica (2011): The National Stadium of Costa Rica (Spanish: "Estadio Nacional de Costa Rica" ) is a multi-purpose stadium in La Sabana Metropolitan Park, San José, Costa Rica.  It is the first modern sport and event arena to be built in Central America.  The stadium was completed in 2011 and officially opened its doors to the public on Saturday, March 26 of that same year, with a capacity of 35,175 seats.  The stadium replaces the original National Stadium.  It also serves as the home stadium of the Costa Rica national football team.

Supporting paragraphs: Silverdome (disambiguation) Pontiac Silverdome
Answer: 1975