Thank you for your question. It is not established that the majority of people will end up in hell. As for the avoidance of creating those who God knew would end up in hell, that is an issue of Divine Wisdom for which we can try to reasonably understand with the assumption that we can know something of that wisdom. The issue could then be understood with reflection into the meaning and implications of free will. There would be no meaning to the creation of beings with free will if none of them had the choice to end up in hell. In this instance it is not accurate to frame the question from the perspective of Divine Mercy alone.
May you always be successful