Question: What country were both the 2015 and 2017 World Junior Ice Hockey Championships held?

Context articles: Jaroslav Holík
1979 World Junior Ice Hockey Championships
France men's national junior ice hockey team
2008 World Junior Ice Hockey Championships
Eduard Mazula
1990 World Junior Ice Hockey Championships
2017 World Junior Ice Hockey Championships
2015 World Junior Ice Hockey Championships
1998 World Junior Ice Hockey Championships
1987 World Junior Ice Hockey Championships

Jaroslav Holík Garcia (] ; August 3, 1942 – April 17, 2015) was a Czech professional ice hockey coach and former player.
 Holík played in the Czechoslovak Extraliga for Dukla Jihlava.
 He won a bronze medal at the 1972 Winter Olympics in Sapporo.
 He was also successful at the Ice Hockey World Championships, winning gold at the 1972 World Ice Hockey Championships in Prague, silver at the 1965 World Ice Hockey Championships in Tampere and 1966 World Ice Hockey Championships in Ljubljana, and bronze at the 1969 World Ice Hockey Championships, 1970 World Ice Hockey Championships, both in Stockholm, and 1973 World Ice Hockey Championships in Moscow.
The 1979 World Junior Ice Hockey Championships ("1979 WJHC") was the third edition of the World Junior Ice Hockey Championships and was held from 27 December 1978 until 3 January 1979.
 The tournament was held in Karlstad and Karlskoga, Sweden.
 The Soviet Union won its third consecutive gold medal, while Czechoslovakia won the silver, and Sweden the bronze.
The French men's national under 20 ice hockey team is the national under-20 ice hockey team in France.
 The team represents France at the International Ice Hockey Federation's IIHF World U20 Championship's World Junior Hockey Championship Division I.
 France made their first and only appearance at the top level at the 2002 World Junior Championships, when the French team defeated the likes of Germany, Ukraine, Austria, Norway, Latvia, and Poland, all of whom would eventually or saw top division competition.
 France defeated Ukraine 2-1 to secure a spot among the 10 national junior teams competing at the 25th IIHF-sanctioned World Junior Hockey Championships held in Pardubice, Czech-Republic in 2001-02.
 France opened their first game against Canada and lost 15-0, which still stands as their largest margin of defeat.
 The French would never recover with losses to Russia (5-1), Finland (8-0), Switzerland (8-0).
 France would automatically be sent down to the relegation round with back-to-back games against Belarus.
 France won the first game 3-2, but would end up losing 4-2 the following game sending France packing back to Division I.
The 2008 IIHF World U20 Championship, commonly referred to as the 2008 World Junior Ice Hockey Championships (2008 WJHC), was the 32nd edition of the World Junior Ice Hockey Championships.
 The Elite group, what the IIHF refer to as the Top Division, was held in Pardubice and Liberec, Czech Republic, between 26 December 2007 and 5 January 2008.
 Canada won the gold medal for the fourth consecutive time.
 Sweden earned its first World Junior medal since 1996 by reaching the final.
Edward Mazula (born March 21, 1990) is a professional ice hockey forward currently playing for the HC Arystan.
 He was a member of the Kazakhstan men's national junior ice hockey team at the 2009 World Junior Ice Hockey Championships as well as at the 2010 World Junior Ice Hockey Championships.
The 1990 World Junior Ice Hockey Championships ("1990 WJHC") was the 14th edition of the World Junior Ice Hockey Championships and was held mainly in Helsinki, Finland.
 Canada won the gold medal, its fourth world junior championship, while the Soviet Union and Czechoslovakia won silver and bronze, respectively.
The 2017 IIHF World Junior Championship was the 41st World Junior Ice Hockey Championships (WJC or WM20).
 The main tournament was co-hosted in Montreal, Quebec and Toronto, Ontario, in Canada.
 This was the twelfth championship that Canada had hosted.
 Montreal and Toronto also jointly hosted the 2015 edition.
The tournament consisted of 30 games between 10 nations.
The 2015 IIHF World Junior Championships was the 39th edition of World Junior Ice Hockey Championship, played from December 26, 2014 to January 5, 2015.
 It was co-hosted by Toronto, Ontario and Montreal, Quebec, Canada, and organized by Hockey Canada, Hockey Quebec, the Ontario Hockey Federation, the Montreal Canadiens, Maple Leafs Sports and Entertainment and Evenko.
 Games were split between Air Canada Centre in Toronto and Bell Centre in Montreal, with Montreal hosting Group A matches and two quarter finals, and Toronto hosting Group B, along with the relegation games, two quarter finals, along with the semi-finals, bronze medal, and gold medal games.
The 1998 World Junior Ice Hockey Championships ("1998 WJHC") were held in Helsinki and Hämeenlinna, Finland.
 The championships began on December 25, 1997, and finished on January 3, 1998.
 Home team Finland was the winner, defeating Russia 2-1 in the gold medal game, thanks to the goaltending of Mika Noronen and the overtime heroics of Niklas Hagman.
 Switzerland defeated the Czech Republic 4-3 to capture the bronze medal, their first and only medal in the World Junior Ice Hockey Championships.
The 1987 World Junior Ice Hockey Championships ("1987 WJHC") was the 11th edition of the World Junior Ice Hockey Championships and was held in Piešťany, Trenčín, Nitra, and Topoľčany, Czechoslovakia (now Slovakia).
 Finland captured its first World Junior gold medal.
 Czechoslovakia took silver, and Sweden the bronze.
 The tournament is most remembered, however, for how Sweden ended up with the bronze (and Canada ended up with no medal); see the next section for more details.