How much of the light falling on a good quality ordinary mirror does it reflect?

1. A good quality mirror may reflect more than 90 percent of the light that falls on it, absorbing the rest. 2. No ordinary silvered mirror reflects everything, which is why a long chain of mirrors dims an image. 3. Total internal reflection is the way to get a surface that reflects all of the light striking it. 4. That is why an optical fibre wall outperforms a silvered mirror for guiding light over long distances. _Source: OpenStax College Physics (CC BY 4.0), Ch 25 "Geometric Optics", section 25.4 Total Internal Reflection_