The World of Sustainability Core 18% 7% 93% utside the World Inside the World Mid-level 65% of Sustainability of Sustainability Periphery 17% Source:The Hartman Group 2007 Sustainability Survey(n=1,606).Th W ld f The World of Source: Th S t i bilit Sustainability he Hartman Group 2007 Sustainability Survey (n=1,606)