Department of Energy classification reviewers at the National Archives examined over 2.5 million pages of previously declassified records earlier this year and found only nine (9) pages that they said contained classified information which should not have been publicly disclosed, according to a new report to Congress (pdf).
This is a vanishingly small error rate of less than a thousandth of a percent, the smallest ever reported by DOE since it began searching for inadvertently released classified nuclear weapons information in declassified files in 1999.
This might be considered well within the boundaries of what is reasonably achievable under a risk management approach to security policy.
Yet the DOE declassified document review program seems predicated on absolute risk avoidance, in which no release of classified information, no matter how outdated or innocuous it may be, is acceptable. And so the reviewers toil on, and public access to historical records at the National Archives remains disrupted.
See the Twenty-First Report to Congress on Inadvertent Disclosures of Restricted Data, U.S. Department of Energy, May 2006 (released in redacted form July 2006).