I might point out, further to that question, that in the period you referred to when Cornell did the study, Panama was on the so-called OECD grey list for not having negotiated enough tax information exchange agreements with other partners. Since then, it has negotiated the minimum number of 12 and is continuing to negotiate more, so that's some indication of some improvement in the situation.
On September 25th, 2012. See this statement in context.