Question: Which chain was founded first Toppers Pizza or Pietro's Pizza?

Context paragraphs:
Pizza 73: Pizza 73 is a Canadian restaurant chain that offers a number of different styles of pizza, along with chicken wings.  It has been operated by Pizza Pizza since 2007.  Toronto-based Pizza Pizza had acquired the restaurant for a total of $CAN70.2 million.  There are 89 locations throughout Western Canada, which include the provinces of British Columbia, Alberta, and Saskatchewan.  The restaurant's name originates from its original phone number: 473–7373.  Founded by David Tougas and Guy Goodwin in 1985, Pizza 73 is headquartered in Edmonton, Alberta, Canada.

Peppes Pizza: Peppes Pizza is a Norwegian pizza chain that serves American style and Italian style pizza.  Peppes is the largest pizza chain in Scandinavia.  The restaurant was founded by two Americans, Louis Jordan and his wife Anne from Hartford, Connecticut.  The restaurant chain is part of Umoe Catering As which consists of restaurants such as Burger King, TGI Fridays, La Baguette and Cafe Opus.  Peppes Pizza is one of the first restaurants that brought foreign food to Norway.  9 million pizzas are served by Peppes each year with deliveries in 11 cities in Norway.  Their menu was first put online in March 1995.  The servings have been described as enough for two people and that the pizza chain is "a cut above the rest".

Rabbe Grönblom: Rabbe Anders Grönblom (May 3, 1950 Helsinki, Finland – June 29, 2015) was a Finland-Swedish businessman who started a successful pizza business in Vaasa, Finland.  His first company—a pizzeria—was called "O sole mio" and it was founded in 1976 in the center of Vaasa.  From there he expanded to a pizza franchise chain first called "Pizzeria N:o 1".  He was known as the "Pizza-emperor" (Pizzakeisari in Finnish), because he was the founder of a well known pizza franchise chain called Kotipizza which was the new name of "Pizzeria N:o 1" which expanded fast outside of Vaasa.  The chain is said to be the biggest one in the Nordic countries.  He was also the founder of a shipping company called RG Line, a hotel chain called Omenahotelli and another pizza chain called Golden Rax Pizzabuffet.  Most of his companies are subsidiaries of Grönblom International LTD, where Rabbe Grönblom acted as director.  Golden Rax Pizzabuffet however is nowadays a part of Finland's largest hotel & restaurant company Restel Oy Ltd, where Rabbe Grönblom sat on the board.  He was also on the board of the Finnish tyre company Nokian Renkaat (since 2003).

Pietro's Pizza: Pietro's Pizza is a small pizza chain in the U.S. state of Oregon.  Founded in 1957, the chain grew to about 80 restaurants and changed owners several times before shrinking to only four stores.  The company is based in Milwaukie, Oregon.

Blackjack Pizza: Blackjack Pizza is a Colorado-based pizza delivery chain founded in 1983 by a former Domino's Pizza employee, Vince Schmuhl, because Domino's Pizza was the only major pizza delivery company in the Rocky Mountain region and he thought customers would appreciate an alternative.  The pizza chain is the largest in Colorado with 800 employees, some of whom work part-time.  On January 1, 2013, Blackjack Pizza was acquired by Askar Brands.

Mr. Jim's Pizza: MrJims.Pizza is a U.S. chain of pizza restaurants based in Farmers Branch, Texas.  Jim Johnson opened the first restaurant in Detroit, Michigan in 1975.  There are currently 42 locations in Louisiana, Texas, North Carolina, Nevada and Wyoming, with the majority located in northern Texas.  MrJims.Pizza is widely known for their crust.  Their hand stretched pizza dough is made fresh in the store daily from flour containing 100% spring wheat.  Every single MrJims.Pizza franchise has online ordering capabilities.  In 2006, MrJims.Pizza introduced a unique new item, Nacho Stix, to their menu.  It quickly became one of their bestsellers, and lead to a resurgence in the popularity of MrJims.

Papa Murphy's: Papa Murphy's, a business based in Vancouver, Washington, United States, is a take-and-bake pizza company.  It began in 1995 as the merger of two take-and-bake pizza companies: Papa Aldo's Pizza (founded in 1981) and Murphy's Pizza (founded in 1981).  The company and its franchisees operate more than 1,300 outlets in the United States and Canada.  Papa Murphy's is the fifth-largest pizza chain in the United States.

Pizza Ranch: The Pizza Ranch, Inc., founded in 1981, is a "fast casual" restaurant chain.  Pizza Ranch offers pizza, chicken, a salad bar, and a pizza and chicken buffet.  Pizza Ranch has over 200 locations in Colorado, Illinois, Iowa, Kansas, Michigan, Minnesota, Missouri, Montana, Nebraska, North Dakota, South Dakota, Wisconsin, and Wyoming.  Pizza Ranch is the largest regional pizza franchise in Iowa, Minnesota, North Dakota, and South Dakota.

Toppers Pizza (American restaurant): Toppers Pizza is a chain of pizzerias in the United States.  The chain was founded by Scott Gittrich in 1991 in Champaign, Illinois, but the original location closed in the mid-1990s.  The first Toppers Pizza location in Wisconsin opened in Whitewater in 1993.  The company is headquartered in Whitewater, Wisconsin.  The first official franchise store opened in Eau Claire, WI in 1997.

Topper's Pizza: Topper's Pizza or Toppers Pizza may refer to one of three pizza chains:

Supporting paragraphs: Toppers Pizza (American restaurant) Pietro's Pizza
Answer: Pietro's Pizza