Mexico has a population of over 113 million people as of 2011, with an average density of 823 people per square kilometer. Mexico City alone has a population of over 19 million, and has a density of nearly 6,000 people per square kilometer. The majority of Mexico's population is Mestizo, with Indigenous and Spanish ancestry. Literacy rates are around 86% of the population. Roman Catholicism is the dominant religion, practiced by 77% of Mexicans. The North American Free Trade Agreement has greatly impacted Mexico's economy by providing access to U.S. markets, though it also increased competition and tied development closely to international economic conditions.