Cafe Perks, known for its "Just Right" size to go coffee, has decided to offer a new size cup known as "Big Sludge". In the month prior to introducing Big Sludge, $917$ cups of Just Right coffee were sold. In the month after the introduction, sales of Just Right decreased to $783$ and Big Sludge sold $432$ cups. Based on historical seasonal patterns, the owner felt confident that Just Right would have sold $933$ cups had Big Sludge not been introduced. Based on this information, what was the cannibalization rate?