Except as otherwise provided in this section, a member’s contribution rate is 5% of the part of the member’s earnable compensation that exceeds the taxable wage base for each year. The contribution rate of a member who is subject to the contributory pension benefit under Part II of this subtitle is 2% of the member’s earnable compensation. The contribution rate of a member who is subject to the Alternate Contributory Pension Selection under Part III of this subtitle is: 3% of the member’s earnable compensation received from July 1, 2006 to June 30, 2007, both inclusive; 4% of the member’s earnable compensation received from July 1, 2007 to June 30, 2008, both inclusive; 5% of the member’s earnable compensation received from July 1, 2008 to June 30, 2011, both inclusive; and 7% of the member’s earnable compensation received on or after July 1, 2011. The contribution rate of a member who is subject to the reformed contributory pension benefit under Part IV of this subtitle is 7% of the member’s earnable compensation.