Two-thirds of data breaches in 2012 could be attributed to negligence or human error. Malicious attacks remain the single highest cause of breaches, with 37% of the intrusion pie. The Ponemon-Symantec study also noted that the average per-record cost of breaches around the world increased to $136 from $130. The most expensive kind of breach is one caused by a malicious attack, but the most expensive is a breach caused by such an attack in the U.S.”]
Source: https://www.csoonline.com/article/2133578/negligence-and-glitches-create-64–of-data-breaches.html