The exact percentage of dark matter in the universe is not known with certainty. However, based on current observational evidence and theoretical models, it is estimated that dark matter constitutes about 26.8% of the total mass-energy content of the universe.
This estimate comes from the latest measurements of the cosmic microwave background radiation, large-scale structure of the universe, gravitational lensing, and other observational data. These observations indicate that the majority of the matter in the universe is in the form of dark matter, which does not interact with light or other electromagnetic radiation, making it difficult to directly detect.
It's important to note that the percentage of dark matter is inferred indirectly through its gravitational effects on visible matter and light. The remaining portion of the universe is believed to consist of about 4.9% ordinary matter (atoms, molecules, etc.) and about 68.3% dark energy, which is responsible for the accelerated expansion of the universe.
Our understanding of dark matter is still evolving, and ongoing research and observations aim to refine our estimates and provide more insights into its nature and properties.