We don't have exit control, so we don't know the number of people who don't return. We know those who claim refugee status, or who ask to stay on humanitarian grounds. The number is significant if you look at the number of refugee claims. Many of them came with visas that we issued. Every day a visa is going to be issued in one of those three missions. Some will remain in Canada and claim refugee status who were originally supposed to be coming to visit family members.
Do we have exact data? No, because we don't have exit control. But every day we get notice of a person who came to visit a sister and on arrival claimed refugee status. It happens every day at almost every mission.