A city or county which levies assessments pursuant to this chapter shall pay to the county tax collector all such assessments levied on real property containing one or more dwelling units occupied by persons and families of low or moderate income; provided, that where such real property contains uses other than residential dwelling units occupied by persons and families of low or moderate income only that portion of the assessment attributable to the portion of the property occupied by persons and families of low or moderate income shall be paid by the city or county. The city or county shall establish a reasonable method for determining such apportionments.