The new entity incorporated all the previous private companies operating in Italy since the end of the 19th century. The nationalization followed a general tendency in Europe after the Second World War: France and Great Britain nationalized their sectors in 1946 and 1957 respectively. This was seen as the only solution for an efficient and reliable electricity supply given the natural monopoly nature of this sector. The new entity, which absorbed more than 1000 previously private companies, had to face a rapid growth of electricity demand during subsequent decade, with consumption rising of about 8% every year. This demand was largely met with fossil-fuel powered plants. This trend changed partly after the 1970s oil crisis, which induced Enel to rethink its energy strategy. More investments were devoted to nuclear energy and electricity started to be imported from France to differentiate the supply. However, nuclear energy was abandoned in 1987 following a popular referendum, while imported energy still covers an important share of electricity consumption. The belief of a more efficient sector with a public monopolistic company progressively reversed since the 1980s. Enel was made into a joint-stock company in 1992, however still fully owned by the Ministry of Economy. The liberation of the electricity sector from government control started in late 1990s following European Union directives. Directive 96/92/CE of 1996 followed the tendency towards privatization. It was based on the adoption of different regulations for production and transmission: production and trading should be free and managed by private companies, while transmission and distribution, being natural monopolies, should be regulated by the state. This first directive suggested a progressive liberalization of the electricity market and the "unbundling", namely the clear separation of monopolistic activities from free-market activities in the companies involved in the electricity sector. This separation was effected by clearly separating budgets for different businesses. The European directive was followed by the Italian legislative decree 79/1999 ("Decreto Bersani") of 1999. The decree created a path towards a complete liberalization of the market through gradual steps. Not only the European directive was followed, but the transition to the free market was planned to be faster, with more than 40% of electricity planned to be traded on the free market by 2002 and with a "corporate" separation of activities. Some of Enel's core activities were passed on other companies. The network was transferred to a new company, Terna, responsible for the management of the system. Moreover, the limit on Enel property share of Terna was set at 20%. Enel eventually sold its remaining share of the company in January 2012.