The fee and tax increases in this Code made by this amendatory Act of the 91st General Assembly that apply to registrations apply to registration year 2001 and thereafter. The registration fees and taxes in existence on the day prior to the effective date of this amendatory Act of the 91st General Assembly apply throughout registration year 2000. All other fee and tax increases in this Code made by this amendatory Act of the 91st General Assembly shall apply beginning January 1, 2000 and thereafter.