In order to obtain this data, I would contact the authors of one of the more recent papers (Masulis et al 2011, for example) or the IRRC at http://irrcinstitute.org/contact/.
The TCL benchmark score and the BC Govscore only seem to be used in one of the major papers about corporate governance. If you want to use the TCL benchmark score, you need a subscription to the database through a company called MSCI, which you can contact at https://www.msci.com/contact-us. The BC Govscore
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