The rate of contribution for participating employers who were participating employers under the provisions of Kan. Stat. Ann. § 74-4901 et seq., and amendments thereto, on July 1, 2009, and for participating employers who affiliate for any purpose on or after July 1, 2009, shall be as provided pursuant to Kan. Stat. Ann. § 74-4920, and amendments thereto, except that such rate of contribution for any such participating employers shall not be less than the rate of contribution the employees of such participating employers as provided in Kan. Stat. Ann. § 74-49,209 and Kan. Stat. Ann. § 74-4920, and amendments thereto.