The property of all private corporations for pecuniary gain shall be taxed in the same way and to the same extent as the property of individuals, but the legislature may provide for the taxation of banks and banking capital, by taxing the shares according to the value thereof (augmented by the accumulations, surplus, and unpaid dividends), exclusive of real estate, which shall be taxed as other real estate. Exemptions from taxation to which corporations are legally entitled at the adoption of this Constitution, shall remain in full force and effect for the time of such exemption as expressed in their respective charters, or by general laws, unless sooner repealed by the legislature. And, domestic insurance companies shall not be required to pay a greater tax in the aggregate than is required to be paid by foreign insurance companies doing business in this state, except to the extent of the excess of their ad valorem tax over the privilege tax imposed upon such foreign companies; and the legislature may impose privilege taxes on building and loan associations in lieu of all other taxes except on their real estate.