of subsection (a)(2), the applicable equivalent rate for each calendar year shall be equal to— (A) in the case of any marijuana product not described in subparagraph (B) which is sold during such year, the applicable rate per ounce of such product (and a proportionate tax at the like rate on all fractional parts of an ounce of such product), and (B) in the case of any marijuana product containing a marijuana derivative which is sold during such year, the applicable rate per gram of tetrahydrocannabinol in such product (and a proportionate tax at the like rate on all fractional parts of a gram of tetrahydrocannabinol in such product). (2) Applicable rate (A) In general For purposes of paragraph (1)(A), the applicable rate per ounce for any calendar year shall be equal to 25 percent of the prevailing sales price of marijuana sold in the United States during the 12-month period ending one calendar quarter before such calendar year, expressed on a per ounce basis, as determined by the Secretary. (B) Marijuana derivatives For purposes of paragraph (1)(B), the applicable rate per gram of tetrahydrocannabinol shall be equal to the quotient obtained by dividing— (i) the applicable rate per ounce (as determined under subparagraph (A)), by (ii) 2.83495. (d) Time of attachment on marijuana products The tax under this section shall attach to any marijuana product as soon as such product is in existence as such, whether it be subsequently separated or transferred into any other substance, either in the process of original production or by any subsequent process. 5902. Definitions For purposes of this chapter: (1) Export warehouse The term export warehouse means a bonded internal revenue warehouse for the storage of marijuana products, upon which the internal revenue tax has not been paid— (A) for subsequent shipment to a foreign country, Puerto Rico, the Virgin Islands, or a possession of the United States, or (B) for consumption beyond the jurisdiction of the internal revenue laws of the United States. (2) Export warehouse