20 percent in each year following the adoption of this provision, and after the expiration of the 4th year such inventories are exempt from taxation. The Legislature may exempt any other personal property, including livestock. 7.??No inheritance tax shall ever be levied. 8.??The Legislature may exempt by law property used for municipal, educational, literary, scientific or other charitable purposes, or to encourage the conservation of energy or the substitution of other sources for fossil sources of energy. 9.??No income tax shall be levied upon the wages or personal income of natural persons. Notwithstanding the foregoing provision, and except as otherwise provided in subsection 1 of this Section, taxes may be levied upon the income or revenue of any business in whatever form it may be conducted for profit in the State. 10.??The Legislature may provide by law for an abatement of the tax upon or an exemption of part of the assessed value of a single-family residence occupied by the owner to the extent necessary to avoid severe economic hardship to the owner of the residence. 11.??The Legislature may provide by law for the determination of the value of improvements to real property for the purposes of taxation upon the transfer, sale or other conveyance of the property as the Legislature determines to be appropriate. [Amended in 1902, 1906, 1942, 1960, 1962, 1974, 1978, 1982, 1986, 1989 and 1990. The first amendment was proposed and passed by the 1899 Legislature; agreed to and passed by the 1901 Legislature; and approved