An investor could have bought a case of Chateaux Margaux 1995 as recently as January 2003 for $895 a case. Assume that annual storage costs are 9$ p.a. per case are payable annually in advance each year. What IRR would an investor receive if this case was subsequently sold at auction by Southey's in January 2015, for a hammer price equivalent of $296 a bottle, less their standard 17.5% auction fee?