availability of oil. From 15,000 miners in 1947, Rhondda had just a single pit within the valleys producing coal in 1984, located at Maerdy. In 1966, the village of Aberfan in the Taff valley suffered one of the worst disasters in Welsh history, referred to today as the Aberfan disaster. A mine waste tip on the top of the mountain, which had been developed over a spring, slid down the valley side and destroyed the village junior school, killing 144 people, 116 of them children. In 1979, Margaret Thatcher became Prime Minister of the United Kingdom. Her policies of free market economics soon clashed with the loss-making, government-owned National Coal Board. In 1984 and 1985, after the government announced plans to close many mines across the UK, mineworkers went on strike. This strike, and its ultimate failure, led to the virtual destruction of the UK's coal industry over the next decade, although arguably costs of extraction and geological difficulties would have had the same result, perhaps a little later. No deep coal mines are left in the valleys since the closure in 2008 of Tower Colliery in the Cynon Valley. Tower had been bought by the workers in 1994, despite government attempts to close it. By 2002, the unemployment rates in the Welsh valleys were among the highest in the whole United Kingdom since the 1980s, and have been seen as a major factor in the rise in drug abuse in the local area, which was highlighted in the national media during the autumn of 2002 and largely linked to drug dealing gangs from Birmingham and Bristol. Present day The Valleys are home to around 30% of the Welsh population, although this is declining slowly because of emigration, especially from the Upper Valleys. The area has a relatively high proportion of residents (over 90% in Blaenau Gwent and Merthyr Tydfil) born in Wales. The area has a slightly younger age profile than Wales as a whole, a result of the lower proportion of elderly residents, and higher rates of teenage pregnancies than elsewhere. In 2004 this put the average age in the Valleys 6 months younger than the Welsh average. The Valleys suffer from a number of socio-economic problems. Educational attainment in the Valleys is low, with a large proportion of people possessing few or no qualifications. high proportion of people report a limiting long-term health problem, especially in the