Pharmaceutical industry:

Drug discovery and development is very expensive; of all compounds investigated for use in humans only a small fraction are eventually approved in most nations by government appointed medical institutions or boards, who have to approve new drugs before they can be marketed in those countries. In 2010 18 NMEs (New Molecular Entities) were approved and three biologics by the FDA, or 21 in total, which is down from 26 in 2009 and 24 in 2008. On the other hand, there were only 18 approvals in total in 2007 and 22 back in 2006. Since 2001, the Center for Drug Evaluation and Research has averaged 22.9 approvals a year. This approval comes only after heavy investment in pre-clinical development and clinical trials, as well as a commitment to ongoing safety monitoring. Drugs which fail part-way through this process often incur large costs, while generating no revenue in return. If the cost of these failed drugs is taken into account, the cost of developing a successful new drug (new chemical entity, or NCE), has been estimated at about 1.3 billion USD(not including marketing expenses). Professors Light and Lexchin reported in 2012, however, that the rate of approval for new drugs has been a relatively stable average rate of 15 to 25 for decades.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". Who reported the stable average rate in 2007?
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