A study by Virginia Tech found that half of all users reused passwords, or used slight modifications of passwords across a range of accounts. The study looked at 28.8 million users and their 61.5 million passwords in 107 services over 8 years. The passwords in use were so weak that more than 16 million password pairs (30% of the modified passwords and all the reused passwords) can be cracked within just 10 guesses. Only about 1/3 of users follow the recommended practice of having a unique password for each online account.”]
Source: https://www.darkreading.com/authentication/more-than-half-of-users-reuse-passwords