The trend towards private philanthropic foundations has seen some of the worlds most powerful past and present leaders lending business and political clout to public-private partnerships for international development. The Bill & Melinda Gates Foundation is the worlds largest private philanthropic foundation. Since its inception in 2000, the foundation has pledged in excess of US$21 billion in grants to projects across the US and in more than 100 countries. Founded in 1998 by the Executive Chairman of the World Economic Foundation, Klaus Schwab, and his wife Hilde, the Schwab Foundation promotes social entrepreneurship as a catalyst for social innovation and progress. Established in 2003, the Clinton Foundation focuses on addressing global climate change, HIV/AIDS in the developing world, childhood obesity and economic opportunity in the US, and economic development in Africa and Latin America. Established in 1913, the Rockefeller Foundation is the forefather of modern philanthropic trusts.