Question: In which year was this studio album by Finnish symphonic power metal band Nightwish released for which the band went on Endless Forms Most Beautiful World Tour?
Context: Endless Forms Most Beautiful is the eighth album by Finnish symphonic power metal band Nightwish.  It was released on March 27, 2015 in Argentina and most of Europe, March 30 in the UK, and March 31 in the US.  The album is the band's first featuring singer Floor Jansen and the first with Troy Donockley as a full-time member.  It was recorded without drummer Jukka Nevalainen, who took a break from the band due to severe insomnia.  Drumming was by Kai Hahto of Wintersun and Swallow the Sun.  The album includes only five Nightwish members, despite its being their first album release as a sextet. Sami Vänskä (born 26 September 1976) is the former bassist of Finnish symphonic power metal band Nightwish. Vehicle of Spirit is a video and audio release from Finnish symphonic metal band Nightwish.  Two shows have been recorded during Endless Forms Most Beautiful World Tour; one at Tampere Stadium (July 31, 2015) and the other at Wembley Arena (December 19, 2015).  Also, various songs were recorded around the world.  It was released on December 16, 2016 in Europe and January 7, 2017 in North America. "Endless Forms Most Beautiful" is a song by Finnish symphonic metal band Nightwish.  It is the second single from their eighth album "Endless Forms Most Beautiful".  The song was announced on April 17, 2015, alongside its release date and cover, and was eventually released on May 8, 2015 together with a lyric video. "Élan" is a single by Finnish symphonic metal band Nightwish, the first from their eighth album "Endless Forms Most Beautiful".  The song marks the first Nightwish song to feature its newest frontwoman, Dutch singer Floor Jansen, on vocals, and also the first to feature Troy Donockley as a full-time member and Kai Hahto as a temporary replacement for Jukka Nevalainen. Wishmaster World Tour was the first world tour by Finnish symphonic metal band Nightwish, from May 15, 2000 to September 15, 2001, with the album "Wishmaster" as the base.  Though the tour itself was very successful, by its end in 2001, it had left the band exhausted and led to a break for the rest of the year before the band started their next tour, "World Tour of the Century", in 2002; the tour comprised 97 gigs in 20 countries. Dark Passion Play World Tour was the fourth world tour by Finnish symphonic metal band Nightwish, taking place from 2007 to 2009 in support of their sixth studio album, "Dark Passion Play", released by Nuclear Blast on September 26, 2007; it was the first tour with former frontwoman Anette Olzon, who joined the band in 2006, after Tarja Turunen's dismissal on October 21, 2005.  During this tour, the band played for the first time in Israel, China, Hong Kong, Lithuania, Luxembourg, Republic of Ireland, Serbia and Croatia. Endless Forms Most Beautiful World Tour was the sixth world tour by Finnish symphonic metal band Nightwish, in support of their eighth studio album, "Endless Forms Most Beautiful". Oceanborn Europe Tour was a concert tour by Finnish symphonic metal band Nightwish from November 12 to December 12, 1999.  The tour is notable for featuring the band's first European concerts.  Oceanborn Europe Tour followed a Finnish leg with 33 shows, the Summer of Wilderness.  In this tour, Nightwish played beside German heavy metal band Rage, and Nightwish was occasionally supported by Finnish singer Tapio Wilska, singing in the songs "The Pharaoh Sails to Orion" and "Devil and the Deep Dark Ocean"; Tuomas Holopainen performed "Beauty and the Beast" and "Astral Romance" beside Nightwish's frontwoman, Tarja Turunen. The First Tour of the Angels was a concert tour by Finnish symphonic power metal band Nightwish from December 31, 1997, to November 13, 1998.  Nightwish played only 8 gigs since Jukka Nevalainen and Emppu Vuorinen were waylaid by their mandatory military draft and Tarja Turunen had not finished her studies.  The male vocals in "Beauty and the Beast", "The Carpenter" and "Astral Romance" were sung by Tuomas Holopainen, beside Tarja.  The band was supported by bassist Samppa Hirvonen and the keyboardist Marianna Pellinen during the tour; in 1998, Samppa was replaced by Sami Vänskä.  There is a bootleg of the Helsinki gig called Live at The Tavastia.
Answer: 2015