a    Projected estimate (medium fertility variant).
b    2015
c    Refers to Seoul Special City.
d    2017
e    2016
f    Data classified according to ISIC Rev. 4.
g    Estimate.
h    Calculated by the Statistics Division of the United Nations from national indices.
i    Excluding water and waste management.
j    2014
k    Data refers to a 5-year period preceding the reference year.
l    Refers to foreign citizens.
m    Data as at the end of December.
n    2009
o    Population aged 3 years and over.
p    Excluding social sciences and humanities.
q    2004
r    2012
s    Development Assistance Committee member (OECD).
t    Provisional data.