public sector agencies are headquartered in the city as well as the High Court of Justiciary and the centres of Scotland's legal establishment. As a centre of Scots law, the legal profession has had a long presence in Edinburgh, with many premises in the New Town belonging to legal practices and firms. Many ancillary economic undertakings and political pressure groups have thus set up around this new seat of government leading to a boom in the recruitment and employment of public sector officials. The City of Edinburgh Council and the National Health Service are the two largest employers in the City. Education Edinburgh is a major centre of education in the United Kingdom, and has been since the establishment of the University of Edinburgh in 1583, with another three major higher education institutions in the city developing later. Education and academic research (including medical research) plays a significant role in the economy of the city. The presence of these educational institutions also attracts many overseas students and those from the rest of the UK. There is currently a student population of 57,850 enrolled in universities across the city. Life sciences and microelectronics in particular and have grown in prominence in recent years. The University of Edinburgh is a leader in the fields of medicine and law, and was a pioneer in British artificial intelligence teaching. Heriot-Watt University specialises in science and engineering and Napier University in the fields of computing and business, as well as creative fields. The city is also home to a number of independent schools, with around one in five school-age pupils attending private institutions. Infrastructure The city is linked internationally by Edinburgh Airport (EDI) which in 2018 saw 14.3 million passengers throughout the year, which makes Edinburgh Airport the busiest Scottish Airport and sixth busiest in the UK. In terms of rail connections, Edinburgh Waverley railway station is the principal mainline station in the city serving over 22.5 million passenger journeys over 2011–12. The city is also well served by its bus service, with Lothian Buses having its headquarters in Edinburgh. Over 70 services run throughout the city, which includes a direct link to the airport and open top buses for city tours. The Edinburgh Trams, completed in May 2014, consist of 15 tram stops along the single 14 km (8.7 mi) line. The route links Edinburgh Airport in the West, to York Place in the