Let's look at it this way: Even if human decisions were influenced by the outside in a 100%. And then you take the human out of that equation and realize that there is no decision. Without human, there is no decision. Influences, no matter how great and many may be, cannot make a decision by itself. Never. Influences don't have the ability to make decisions, that ability only has the human.

It makes no sense to say that everything else except ourselves determines what we do. And if we applied that same logic for everything else in the universe, for all atoms, for all particles, we would realize that everything is moving because, not of itself, but of something else, and therefore, despite nothing being the cause of nothing, everything is caused.

Or is it that we have the capacity to influence the decisions of others, to exist simply as influence, but not to influence our own? Or maybe we cannot influence others, or do anything for ourselves, to the point of affirming that "I", whatever I am, or rather what I am not, does not exist? Because if I existed, I could surely influence, even a little, what I am doing directly. If I am not able to influence even that, why would I even think I exist?

More magical than free will, it seems to me to say that everything we do happens because of something other than us, and all things in the world are moved by things other than themselves, and that everything that happens is caused by the past, but that the past itself happened because of nothing. All this and more, it seems that it cannot stand on its own unless some kind of God is introduced that makes all these things possible.

We cannot know for sure what percentage of free will we have, but what we can know is that there is in fact freedom, and that we are the cause of our decisions, the rest is just a matter of degrees.