The modern, private enterprise economy of Belgium has capitalised on its central geographic location, highly developed transport network, and diversified industrial and commercial base. The first country to undergo an industrial revolution on the continent of Europe in the early 19th century, Belgium developed an excellent transportation infrastructure of ports, canals, railways, and highways to integrate its industry with that of its neighbors. Industry is concentrated mainly in the populous Flanders in the north, around Brussels and in the two biggest Walloon cities, Liège and Charleroi, along the sillon industriel. Belgium imports raw materials and semi-finished goods that are further processed and re-exported. Except for its coal, which is no longer economical to exploit, Belgium has few natural resources other than fertile soils. Nonetheless, most traditional industrial sectors are represented in the economy, including steel, textiles, refining, chemicals, food processing, pharmaceuticals, automobiles, electronics, and machinery fabrication. Despite the heavy industrial component, services account for 74.9% of GDP, while agriculture accounts for only 1% of GDP.