South Korea was ranked the world's twelfth biggest economy last year, down one spot from a year earlier.According to the World Bank, South Korea's gross domestic product last year was more than one.five-three trillion U.S. dollars.GDP is the sum of the total value of all final goods and services produced in a certain period of time.South Korea's ranking has fluctuated over the years.It reached 10th in 2005, before slumping to 15th in 2008.And from 2015 to 2016, it rebounded to 11th.South Korea's gross national income last year jumped 14 spots from a year earlier,…coming in at almost 28,400 dollars.United States topped the GDP list.China was second.