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As per the article you posted NA holds the largest volume of said energy stock, but is only ranked #6 and #7 respectively for exporting.https://en.wikipedia.org/wiki/List_of_countries_by_natural_gas_exports
https://en.wikipedia.org/wiki/List_of_countries_by_oil_exports
Maybe "hoarding" is too strong of a term, but reluctant sellers perhaps?

That's because we aren't... Not at all. We keep increasing our output. It's capitalism. If we can make a buck, it's going to find a way to be produced.