NOTE: NA means not applicable, as the country has no refining capacity.
aEntries are those from USGS, 2009, unless otherwise specified and are current estimates based on available information. They are not certified by any accrediting institution.
bIncludes measured and probable reserves rather than measured and indicated, as for other countries.
cConservative estimates based on planned liquid helium plant capacity (see discussion in text) and a 25-year minimum plant productive life.
dAccording to information compiled by the DOE’s Energy Information Administration, as discussed in the text.