a    Including Christmas Island, Cocos (Keeling) Islands and Norfolk Island.
b    Including Norfolk Island.
c    2017
d    Refers to Significant Urban Areas as of 2001.
e    2018
f    Data classified according to ISIC Rev. 4.
g    Estimate.
h    Weighted average of index values computed for the 8 capital cities.
i    Calculated by the UN Statistics Division from national indices.
j    Break in the time series.
k    2016
l    Data refer to fiscal years ending 30 June.
m    2014
n    Areas not elsewhere specified.
o    Data refers to a 5-year period preceding the reference year.
p    2015
q    Data as at the end of December.
r    2001
s    Population aged 15 years and over.
t    Population aged 15 to 72 years.
u    2004
v    Excluding overseas territories.
w    Excluding nationals residing abroad and crew members.
x    Development Assistance Committee member (OECD).