(FILES) This file photo taken on July 24, 2016 shows International Monetary Fund (IMF) managing-director Christine Lagarde waiting to pose for a "family photo" at the G20 finance ministers meeting in Chengdu, in China's Sichuan province. The head of the International Monetary Fund on September 1, 2016 called on global leaders to take "forceful" action to revive the world economy, sounding a stark warning ahead of this weekend's G20 summit. Christine Lagarde, the IMF managing director, said that as of 2016, global economic growth had stagnated for five years below the 3.7 percent average that prevailed between 1990 and 2007. / AFP PHOTO / FRED DUFOURFRED DUFOUR/AFP/Getty Images