Over at the website Law and Liberty you’ll find my short essay on tax havens (http://www.libertylawsite.org/2017/06/30/in-trusts-we-trust/).
I have no idea of the true percentage but I would not be remotely surprised if pretty much 100% of all haute couture was purchased with monies drawn from tax havens. My essay examines the tricky morality of tax havens through the thinking of Edmund Burke.