Liberia has the highest ratio of foreign direct investment to GDP in the world, with US$16 billion in investment since 2006. Following Sirleaf's inauguration in 2006, Liberia signed several multi-billion-dollar concession agreements in the iron ore and palm oil industries with numerous multinational corporations, including ArcelorMittal, BHP and Sime Darby. Palm oil companies like Sime Darby (Malaysia) and Golden Veroleum (USA) have been accused of destroying livelihoods and displacing local communities, enabled by government concessions. Since 1926 Firestone has operated the world's largest rubber plantation in Harbel, Margibi County. As of 2015 it had more than 8,000 mostly Liberian employees, making it the country's largest private employer.