Dark data is all the information companies collect but never use—often 60-80%...

https://lima-wiki.win/index.php/What_Is_the_Fastest_Way_to_Spot_Files_Not_Accessed_in_Years%3F

Dark data is all the information companies collect but never use—often 60-80% of their stored data. This inactive data costs businesses an average of $2.5 million a year in storage and management expenses