There is no definitive answer to the question of what percentage of sleep quality is good. This is because sleep quality is a subjective measure that can vary from person to person.
Some people might consider 8 hours of deep, restful sleep to be good, while others might only feel rested after 10 hours. It's important to pay attention to your own body and its needs when it comes to sleep quality. There are some general guidelines that can help you determine if you're getting enough good sleep, but it's important to tailor them to your own needs.
One common measure of good sleep quality is the amount of time spent in different stages of sleep. Generally, adults need around 7-8 hours of uninterrupted slumber each night in order to feel rested and energetic the next day.