The Mexican govt reports what percentage of the national gdp each state accounts for.
So, the combined GDP of DF, Estado de México and Morelos is 27.3% of the national GDP( which waa $1.291 Trillion in 2014 according to the IMF)
So...
Greater Mexico City
2014 Gross Product: $352.443 Billion
2014 Population: 25,804,000
2014 Per Capita GDP: $13,658
SecretarÃa de EconomÃa - Distrito Federal