The town council of North Kingstown may, by ordinance, exempt from taxation the real property situated in the town which is owned and occupied by any person over the age of sixty-five (65) years, and the exemption may be in an amount up to but not in excess of thirty thousand dollars ($30,000) of valuation and only one exemption is allowed to co-tenants, joint tenants, and tenants by the entirety even though all or more than one of them are sixty-five (65) or more years of age and occupy the property. In addition to a requirement of domicile within the town of North Kingstown at the time of making application for the exemption, the ordinance may also require that an applicant for the exemption must be a resident of the town for a period of up to but not in excess of twenty (20) years prior to the date of assessment for the year for which the exemption is claimed; and the ordinance may also require that an applicant for the exemption must have owned and had title to the real estate where he or she resided during any period of residency required by the ordinance. The ordinance may also provide for a graduated schedule of increasing exemptions, the largest of which may not exceed thirty thousand dollars ($30,000) of valuation, which may be based on a graduated schedule of the number of years, up to but not in excess of twenty (20), an applicant for the exemption has resided in the town and/or owned and had title to real estate where he or she resides. The exemption provided in accordance with the provisions of this section is in addition to any other exemption to which a person may be entitled under any other law or ordinance.