* Our Sun is the closest star. It's the only star in our solar system, and all other stars are much, much farther away.
* Visibility is subjective. What stars are visible depends on your location, light pollution, time of year, and even your eyesight. Even in ideal conditions, only a small percentage of stars are actually visible to the naked eye.
* Vast distances. Most stars are incredibly far away, even those we can see. Even the closest star system after our Sun, Alpha Centauri, is over 4 light-years away, making it practically impossible for any star to be closer than our own.
In short, there are no stars closer to Earth than our Sun, so the percentage is zero.
