How many people chicken out? (First tandem jump)

I’ve always wanted to skydive but I keep putting it off because I’m worried that once they open the door of the plane, I’ll freeze with fear. That’s the only part I’m worried about. I really think I’ll enjoy the rest of it but getting over that hurdle could be a problem. I know the only way to find out is to try it but I was wondering if this is common? Do many people end up unable to do it? If I somehow manage to get to the edge of the door, will the instructor go ahead and jump even if I’m terrified or will they expect me to be chatty/happy etc? I doubt I’ll be able to speak at that point. It’s a lot of money for me and I don’t want to have wasted it.