The Lottery's chief operations officer, Gary Gonder, said in a late Tuesday night email to The Associated Press that the discrepancy between rising sales and declining education funding is attributable partly to differing profit margins and prize payouts in Lottery games. Scratch-off games comprise about two-thirds of the Lottery's sales and typically have a higher percentage payout in prizes — and thus transfer a lower percentage to education — than other more profitable games such as Powerball. A 1992 voter-approved amendment to the Missouri Constitution requires all Lottery proceeds not used for prizes or administration expenses to go to public schools and higher education.