According to the passage, what has made America’s system of higher education a great success?

The decentralization, diversity, academic freedom and shared governance that have evolved over the past two centuries have made America’s system of higher education one of the most accessible and democratic in the world. Today educators from around the globe are turning to U.S. institutions of higher learning for inspiration.

More than 10 months after the end of major military operations in Iraq, American teams have still not found conclusive evidence that Iraq had any chemical, biological or nuclear weapons, raising doubts about one of the Bush administration’s main arguments for going to war. Since he resigned from his post last month, Dr. Kay has said he believes that Iraq largely abandoned the production of weapons of mass destruction after the first Gulf War, and that it gradually destroyed its remaining stockpiles during the 1990’s.