A meeting of the association must be held at least once each year. Special meetings of the association may be called by the president, a majority of the executive board, or by unit owners having twenty percent, or any lower percentage specified in the bylaws, of the votes in the association. Not less than ten nor more than fifty days in advance of any meeting, the secretary or other officer specified in the bylaws shall cause notice to be hand delivered or sent postage prepaid by United States mail to the mailing address of each unit or to any other mailing address designated in writing by the unit owner. The notice of any meeting must state the time and place of the meeting and the items on the agenda, including the general nature of any proposed amendment to the declaration or bylaws, any budget changes, and any proposal to remove a director or officer.