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Though it is quite difficult to calculate the overall damage caused by ransomware in 2016 , some researchers state that cybercriminals received over $ 1 billion in ransom payments last year .
 last year: time; cybercriminals: attacker; over $ 1 billion: price
Given event type and trigger, please tell me the arguments of all the listed option. Output format is "name1: role1; name2: role2". 
Event type: ransom 
  Option: victim, attacker, payment method, attack pattern, damage amount, tool, time, price, place 
Text: {0} 
Answer:
 last year: time; cybercriminals: attacker; over $ 1 billion: price