(2) In all other cases, the entire value of the property is included except such part of the entire value as is attributable to the amount of the consideration in money or money's worth furnished by the other joint owner or owners. See § 20.2043-1 with respect to adequacy of consideration. Such part of the entire value is that portion of the entire value of the property at the decedent's death (or at the alternate valuation date described in section 2032 which the consideration in money or money's worth furnished by the other joint owner or owners bears to the total cost of acquisition and capital additions. In determining the consideration furnished by the other joint owner or owners, there is taken into account only that portion of such consideration which is shown not to be attributable to money or other property acquired by the other joint owner or owners from the decedent for less than a full and adequate consideration in money or money's worth. The entire value of jointly held property is included in a decedent's gross estate unless the executor submits facts sufficient to show that property was not acquired entirely with consideration furnished by the decedent, or was acquired by the decedent and the other joint owner or owners by gift, bequest, devise, or inheritance.