[ghshephard]

Gates isn't being measured as the most significant philanthropist because of how much money he is giving away, inflation adjusted or otherwise. He isn't even measured that way because he's also directing much of Warren Buffet's (and others) wealth towards philanthropy; those those are significant accomplishments.

Rather, he's being measured as the most significant philanthropist, because his underlying belief systems, is so all encompassing:

From: [1]

Guided by the belief that every life has equal value, the Bill & Melinda Gates Foundation works to help all people lead healthy, productive lives. In developing countries, it focuses on improving people’s health and giving them the chance to lift themselves out of hunger and extreme poverty. In the United States, it seeks to ensure that all people—especially those with the fewest resources—have access to the opportunities they need to succeed in school and life.

[1] http://www.gatesfoundation.org/Who-We-Are/General-Informatio...