Facing creative stagnation and a backlash following their documentary/double album, Rattle and Hum (1988), U2 reinvented themselves in the 1990s through a new musical direction and public image. Beginning with their acclaimed seventh album, Achtung Baby (1991), and the multimedia-intensive Zoo TV Tour, the band integrated influences from alternative rock, electronic dance music, and industrial music into their sound, and embraced a more ironic, flippant image. This experimentation continued through their ninth album, Pop (1997), and the PopMart Tour, which were mixed successes. U2 regained critical and commercial favour with the records All That You Can't Leave Behind (2000) and How to Dismantle an Atomic Bomb (2004), which established a more conventional, mainstream sound for the group. Their U2 360° Tour of 2009–2011 set records for the highest-attended and highest-grossing concert tour in history. The group most recently released the companion albums Songs of Innocence (2014) and Songs of Experience (2017), the former of which received criticism for its pervasive, no-cost release through the iTunes Store.