FBI Special Agent Joel DeCapua used bitcoin wallets and ransom notes collected by the FBI to calculate how much money was paid in ransom payments over the past 6 years. Ryuk stood out head and shoulders above the rest with payments totaling $61.26 million. Crysis/Dharma at $24.48 million and then Bitpaymer at $8.04 million. De Capua also offered recommended tips on how companies can defend themselves against ransomware. Ransom attacks account for 70-80% of network breaches.
Source: https://www.bleepingcomputer.com/news/security/fbi-says-140-million-paid-to-ransomware-offers-defense-tips/