Cumulative sales of plug-in electric vehicles (PEVs), including all-electric (EVs) and plug in hybrids (PHEVs), have been growing at an increasing rate, particularly in the last three years. From the introduction of the first mass-market EVs and PHEVs in December of 2010, it took about eight years for cumulative PEV sales to reach 1 million. After that, it took less than three years to reach 2 million, just over a year to reach 3 million, and only nine months to reach 4 million cumulative sales. 

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