Detailed Instructions: In this task you are given data in the tabular format and a question. Write the answer to the question based on the information in the table.
Q: Table: ['Year', 'Company', 'Number of Members Affected', 'Duration of Strike', 'Notes']. ['1955', 'Southern Bell Telephone Co.', '50,000', '72 days', "Strike was in answer to management's effort to prohibit workers from striking."]. ['1968', 'AT&T', '200,000', '18 days', 'Wage increases to compensate for cost of living, and medical benefits won']. ['1971', 'Bell System', '400,000', '1 week', 'Cost of Living Allowance (COLA) won for workers']. ['1983', 'Bell System', '600,000', '22 days', 'Last contract with the Bell System before its breakup. Bell System sought givebacks. The contract resulted in Wage increases, employment security, pension, and health improvements.']. ['1986', 'AT&T', '175,000', '25 days', 'COLA clause suspended in contract - former Bell System contracts vary substantially from the AT&T contract.']. ['1989', 'AT&T', '175,000', 'n/a', 'Child and elder care benefits added to contract. COLA clause removed from contract']. ['1989', 'NYNEX', '175,000', '17 weeks', 'Strike was due to major health care cuts by NYNEX']. ['1998', 'US West', '34,000', '15 day', 'Strike was due to mandatory overtime demands and forced pay-for-performance plan. Overtime caps were won.']. ['2000', 'Verizon', '80,000', '3 weeks', 'Strike was due to mandatory overtime demands. Provisions for stress were won.']. ['2011', 'Verizon', '45,000', '13 days', 'Strike was due to major wage and health care cuts by Verizon, a forced pay-for-performance plan and movement-of-work job security provisions. Contract extended.']. ['2012', 'AT&T', '20,000', '2 Days', 'AT&T West; California, Nevada, and AT&T East; Connecticut - Unfair labor practice strike during contract negotiations.']. Question: what years had strikes occur to affect communications workers of america?
A:
['1955', '1989', '1998', '2000', '2011', '2012']