Using this metric, analysis of almost 30,000 total energies in the Materials Project indicated that 50.5% of experimentally observed structures are metastable with respect to competing phases with a median energy of 15 meV/atom above the convex hull. Since 90% of the metastable structures were observed to have energies of less than 67 meV/atom above the convex hull, a metastablity window of 100 meV/atom is often assumed for a candidate material to be 'accessible'.