In 2015 the same McDonald's Big Mac is sold at $4.79 in the U.S., and $3.11 in Mexico (price of local currency converted to U.S. dollars). Suppose the Big Mac represents a market basket of goods through which the purchasing power of $1 in two countries can be compared. Given Mexico's nominal GDP in 2015 is roughly $1.144 trillion, what is Mexico's GDP level adjusted by Purchasing Power Parity (PPP)?