I do not know how many altogether.
But I do know one . . . cousin and friend, 20 years old - had a motorcycle wreck. Was okay except for a broken leg that had bled too much before getting to the hospital. Doctors said blood was required - he and his parents refused. So he did not make it. This was their second child they had lost to a car wreck. We all thought after their oldest daughter died that they would do anything to keep their remaining children healthy and whole. Nope.
So hard to think that he would still be here if they would have just said yes. To me it feels like a waste of life. It is a gift from God that he made our bodies able to share blood, organs, plasma, etc. They willingly turned away that gift.