Question: How many teams are part of the football league in which Roland Gerber spent seven seasons?

Context paragraphs:
Adrian Klemm: Adrian William Klemm (born May 21, 1977) is a former National Football League offensive lineman, who played for the New England Patriots and Green Bay Packers Klemm served as the offensive line coach for four seasons at Southern Methodist University before serving in the same position at UCLA from 2012 to 2016.  He is perhaps best known for being drafted by the New England Patriots in the second round of the 2000 NFL Draft, the same draft in which they selected Tom Brady in the sixth round.  Klemm spent seven seasons in the NFL, winning three Super Bowls as a member of the Patriots.

Roland Gerber: Roland Gerber (20 May 1953 – 24 February 2015) was a German football coach and a former player.  He spent seven seasons in the Bundesliga with 1.  FC Köln and SV Darmstadt 98.

Nick Folk: Nicholas Alexander Folk (born November 5, 1984) is an American football placekicker for the Tampa Bay Buccaneers of the National Football League (NFL).  He was drafted by the Dallas Cowboys in the sixth round of the 2007 NFL Draft.  He played college football at Arizona.  Folk was selected to be the NFC kicker in the Pro Bowl as a rookie in 2007.  He spent seven seasons with the New York Jets, ranking second on the franchise's all-time points list with 729.

Jim Gorsek: James Gorsek (born October 12, 1955 in Portland, Oregon), known as Jim Gorsek or Jimmy Gorsek, is a former American soccer goalkeeper.  He spent seven seasons in the North American Soccer League, seven seasons in the Major Indoor Soccer League and two in the Continental Indoor Soccer League.  He also earned two caps with the U.S. national team in 1985.

Gale Sayers: Gale Eugene Sayers (born May 30, 1943) is a former professional American football player who earned acclaim both as a halfback and return specialist in the National Football League (NFL).  In a brief but highly productive NFL career, Sayers spent seven seasons with the Chicago Bears from 1965 to 1971, though multiple injuries effectively limited him to five seasons of play.  He was known for his elusiveness and agility, and was regarded by his peers as one of the most difficult players to tackle.

Bundesliga: The Bundesliga ] (lit.  English: "Federal League" , sometimes referred to as the Fußball-Bundesliga ] or 1.  Bundesliga ] ) is a professional association football league in Germany and the football league with the highest average stadium attendance worldwide.  At the top of the German football league system, the Bundesliga is Germany's primary football competition.  The Bundesliga comprises 18 teams and operates on a system of promotion and relegation with the 2.  Bundesliga.  Seasons run from August to May.  Most games are played on Saturdays and Sundays, with a few games played on weekdays.  All of the Bundesliga clubs qualify for the DFB-Pokal.  The winner of the Bundesliga qualifies for the DFL-Supercup.

Richard Harris (American football): Richard Drew Harris (January 21, 1948 – July 26, 2011) was an American football defensive end who played seven seasons in the National Football League.  He was and All-American in 1970 for Grambling and was drafted in the first round (5th overall pick) of the 1971 NFL Draft by the Philadelphia Eagles.  He was named All-Rookie in 1971, playing defensive end.  Harris spent seven seasons as a defensive end in the NFL, the first three with the Philadelphia Eagles, the next two with the Chicago Bears and the final two with the Seattle Seahawks.

Don McPherson: Donald G. McPherson (born April 2, 1965) is a former National Football League and Canadian Football League quarterback.  He spent seven seasons in the NFL and CFL with the Philadelphia Eagles, Houston Oilers, Hamilton Tiger-Cats, and Ottawa Rough Riders.

Danton Cole: Danton Edward Cole (born January 10, 1967 in Pontiac, Michigan) is a retired American professional hockey player and the current Head Coach of the Michigan State Spartans men's hockey team.  He had guided the USA Hockey Under-18 team to a pair of gold medals and a bronze medal at the IIHF World U18 Championships during his seven seasons at the helm from 2010 to 2017.  As a player, he spent seven seasons in the National Hockey League (NHL) with the Winnipeg Jets, Tampa Bay Lightning, New Jersey Devils, New York Islanders and Chicago Blackhawks.  He played right wing and shot right-handed.

Trevor Dawkins: Trevor Dawkins (born 7 October 1945 in Thorpe Bay, Essex) is an English retired professional footballer who played as a defender or in midfield.  He spent seven seasons in the Football League, five in South Africa, and seven in the United States, most in indoor leagues.  Following his retirement in 1985, he coached for fourteen years in the U.S. indoor leagues.  He was the 1986 AISA Coach of the Year, 1991 MISL Coach Of The Year and 1996 CISL Coach of the Year.

Supporting paragraphs: Roland Gerber Bundesliga
Answer: 18