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The 21.5 million current and former federal employees impacted by the massive data breach in 2015 may never know if they will be targeted based on the information stolen from the Office of Personnel Management .
 ( data breach: data breach,  21.5 million: number of victim, 2015: time, federal employees: victim) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: phishing, data breach, ransom, discover vulnerability, patch vulnerability, Arguments type: vulnerable system, capabilities, vulnerability, number of victim, issues addressed, compromised data, damage amount, common vulnerabilities and exposures, victim, patch number, number of data, tool, discoverer, time, purpose, place, payment method, releaser, vulnerable system version, attacker, supported platform, patch, price, vulnerable system owner, trusted entity, attack pattern. 
Text: {0} 
Answer:
 ( data breach: data breach,  21.5 million: number of victim, 2015: time, federal employees: victim) 