To incentivize the construction of opportunity housing units, a multiple-family development that includes at least 9% of its total dwelling units affordable to households at or below 60% of AMI may reduce the required number of storage spaces outside the dwelling unit by 50% provided that the development agreement pursuant to § 9.35 provides that the owner will make storage space accessible to the opportunity housing units without charge. A multiple-family development that includes at least 20% of its total dwelling units affordable to households at or below 50% of AMI may reduce the required number of storage spaces outside the dwelling unit by 75%. A multiple-family development that includes at least 10% of its total dwelling units affordable to households at or below 30% of AMI may reduce the required number of storage spaces outside the dwelling unit by 90%.