Cleveland's current graduation rates are also higher than the statistics cited in the new report, school district spokesman Ben Holbert said.
Spellings and others have previously said a revised No Child Left Behind law should make states provide graduation data in a more uniform way. However, efforts to rewrite the law on Capitol Hill have stalled.
Under the 2002 law, schools that miss progress goals face increasing sanctions, including forced use of federal money for private tutoring, easing student transfers, and restructuring of school staff.
The research behind the report out Tuesday was conducted by Editorial Projects in Education, a Bethesda, Md., nonprofit organization, with support from America's Promise Alliance and the Bill & Melinda Gates Foundation.
The alliance is based on a joint effort of nonprofit groups, corporations, community leaders, charities, faith-based organizations and individuals to improve children's lives.