In 2012, US production accounted for 80% of the global volume. The amount of peppermint oils produced in 2016 was 5.8 million pounds!
Most US peppermint oil comes from Washington (35%), Oregon (27%) and Idaho (21%). Minor producers are Indiana, California and Wisconsin (6%, 3% and 3% respectively).
Peppermint oil from US grown mint is high in menthol and has a pleasant flavor profile, which is why it is favored by the confectionary industry and used to flavor mints, chocolates and other sweet delights. Interestingly, mint flavor is usually achieved by adding peppermint oil without any synthetics.
Average FEMA GRAS maximums for peppermint oil are 0.12% for hard candy, 0.83% for chewing gum and 0.01% for ice cream. http://www.femaflavor.org/
Rectified peppermint oil is preferred by the food flavoring industry. The oil is re-distilled in order to remove minor constituents, such as mint sulfide, that do not taste so good.
Both rectified and unrectified oils are used in the aromatherapy industry for example as a digestive aid, for pain and nausea, and to relieve itching.