Leeds is the largest city in the county of West Yorkshire in Northern England, approximately 170 mi north of central London. Leeds has one of the most diverse economies of all the UK's main employment centres and has seen the fastest rate of private-sector jobs growth of any UK city. It also has the highest ratio of private to public sector jobs of all the UK's Core Cities, with 77% of its workforce working in the private sector. Leeds has the third-largest jobs total by local authority area, with 480,000 in employment and self-employment at the beginning of 2015. Leeds is ranked as a High Sufficiency level city by the Globalization and World Cities Research Network. Leeds is the cultural, financial and commercial heart of the West Yorkshire Urban Area. Leeds is served by five universities, it has the UK's fourth largest student population and the country's fourth largest urban economy.