In general, 14 percent of people have honked for a "Honk if you ..." bumper sticker. But among those who say that in their romantic relationships, it's usually them, not the other person, who does the breaking up, 30 percent have honked for a "Honk if you ..." bumper sticker.
Based on a survey of 105 people who say that in their romantic relationships, it's usually them, not the other person, who does the breaking up and 306 people total.