Hamas rocket attacks, and the opening of the border crossings into the Gaza Strip. Under the Reagan administration, the U.S. withdrew from UNESCO, and withheld its dues to encourage the UN to repeal Resolution 3379, which it did in 1991. The U.S. was—and continues to be—the member state levied most heavily by the UN, so U.S. policymakers expected this strategy to be an effective way to oppose Soviet and Arab influence over the UN. When the UN repealed Resolution 3379, the U.S. resumed dues payments, but not before the U.S. had accumulated significant and controversial arrears. Public opinion Polls have repeatedly gauged public opinion in the U.S. regarding the UN. In the 1950s and 1960s more supportive attitudes were found among the college-educated, more prosperous, and the politically better informed. Distrust was more common among other groups. According to Gregory G. Holyk, "Approval of UN performance dropped to an all-time low between 2003 and 2007, after the contentious debate over the use of force against Iraq. Nonetheless, support for the UN has remained strong because the U.S. public differentiates between criticism of UN performance and support for the general purpose and aims of the UN." Arrears The UN has always had problems with members refusing to pay the assessment levied upon them under the United Nations Charter, but the most significant refusal in recent times has been that of the United States. After prolonged negotiations, the U.S. and the UN negotiated an agreement whereby the United States would pay a large part of the money it owes, and in exchange the UN would reduce the assessment rate ceiling from 25% to 22%. The reduction in the assessment rate ceiling was among the reforms contained in the United Nations Reform Act of 1999 or Helms-Biden Act, which links payment of $926 million in U.S. arrears to the UN and other international organizations to a series of reform benchmarks. Of the U.S. arrears to the UN totaling over $1.3 billion, $612 million was payable under Helms-Biden. The remaining $700 million resulted from various legislative and policy withholdings. Under Helms-Biden, the U.S. paid $100 million in arrears to the UN in December 1999; release of the next $582 million awaited a legislative revision to Helms-Biden, necessary because the benchmark requiring a 25 percent peacekeeping assessment rate ceiling was not quite achieved. The U.S. also sought elimination of the legislated 25 percent cap on