a    2017
b    2019
c    2018
d    Estimate.
e    Calculated by the UN Statistics Division from national indices.
f    2016
g    Data refers to a 5-year period preceding the reference year.
h    Including refugees.
i    Data as at the end of December.
j    2011
k    2014
l    Data are as at 1 January of reporting year.
m    Users in the last 3 months.
n    Arrivals by air.