Pioneers of the new wave of British heavy metal, Iron Maiden achieved initial success during the early 1980s. After several line-up changes, the band went on to release a series of UK and US platinum and gold albums, including 1982's The Number of the Beast, 1983's Piece of Mind, 1984's Powerslave, 1985's live release Live After Death, 1986's Somewhere in Time and 1988's Seventh Son of a Seventh Son. Since the return of lead vocalist Bruce Dickinson and guitarist Adrian Smith in 1999, the band have undergone a resurgence in popularity, with their 2010 studio offering, The Final Frontier, peaking at No. 1 in 28 countries and receiving widespread critical acclaim. Their sixteenth studio album, The Book of Souls, was released on 4 September 2015 to similar success.