(a) The articles of incorporation or a bylaw adopted by the shareholders may provide for staggering the terms of the directors by dividing the total number of directors into two or three groups, with each group containing one-half or one-third of the total, as near as may be. In that event, the terms of directors in the first group expire at the first annual shareholders' meeting after their election, the terms of the second group expire at the second annual shareholders' meeting after their election, and the terms of the third group, if any, expire at the third annual shareholders' meeting after their election. At each annual shareholders' meeting held thereafter, directors shall be chosen for a term of two years or three years, as the case may be, to succeed those whose terms expire.

(b) If directors have staggered terms and the number of directors is thereafter changed:

(1) Any increase or decrease in the number of directors shall be so apportioned among the classes as to make all classes as nearly equal in number as possible; and

(2) When the number of directors is increased and any newly created directorships are filled by the board, the terms of the additional directors shall expire at the next election of directors by the shareholders.