The Secretary of State shall retain the signature sheets of a filed initiative or referendum petition with a copy of the state measure. If the measure is approved by the people, the signature sheets and copy of the measure shall be bound with a certified copy of the Governor’s proclamation declaring the measure approved. A copy of the measure and the Governor’s proclamation shall be preserved as a permanent public record. The signature sheets shall be preserved for six years. [1979 c.190 § 152]