Source: University of Pennsylvania
Release: Penn World Table 7.1
For more information and proper citation see http://www.rug.nl/research/ggdc/data/pwt/pwt-7.1
Source Indicator: cgnp
University of Pennsylvania, Ratio of GNP to GDP for Afghanistan [GNPGDPAFA156NUPN], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/GNPGDPAFA156NUPN, October 21, 2017.