Throughout this period association football, generally referred to as football, was the most popular sport in the UK. The four nations of the UK retained the separate national teams and league systems that they had had since the early days of the sport's codification. The rise of football hooliganism, which had started to come to prominence in the 1970s, continued to mar the game into the 1980s and reached a nadir in the Heysel Stadium disaster, when Liverpool fans hooliganism, combined with poor policing and infrastructure, led to the deaths of 39 Juventus fans before the European Cup final, in May 1985. This resulted in English clubs being banned from European competitions for five years. Welsh clubs playing in the English league system, who could qualify for the European Cup Winners' Cup via the Welsh Cup, were unaffected by the ban, as were clubs from Scotland and Northern Ireland. Attendances at professional matches dropped during the beginning of this period, with the finger of blame pointed not only at increasing hooliganism, but also the deteriorating state of many stadiums. Despite the Guide to Safety at Sports Grounds being published in 1973, following the 1971 Ibrox disaster, safety standards at many football grounds were poor, culminating in the Bradford City stadium fire in 1985 and the Hillsborough disaster in 1989, in which 56 and 96 people, respectively, were killed as a consequence of poor stadium safety. Recommendations from the subsequent Taylor Report were acted upon, and eventually all top-flight stadiums in England, Scotland, and Wales became all-seated. The structure of league football in England was radically altered in 1992 when the clubs of the Football League First Division resigned en masse in 1992 to form the Premier League, which became the new top division in England. The new league assigned TV rights to Sky TV as a revenue-raising exercise, which was a relatively new concept in the UK. These domestic rights issues were followed in time with a succession of international rights packages and the Premier League became the most watched football league in the world. In Scotland, a similar split occurred in 1998 when the Scottish Premier Division split to form the Scottish Premier League. It was abolished in 2013, when it re-merged with the Scottish Football League merged to form the Scottish Professional Football League. Prior to 1992 there was no national league in Wales, just a cup competition,