Boston-based Safety Insurance Group reported fourth-quarter 2012 operating earnings of $9.6 million, or 62 cents per share — surpassing year-earlier earnings of $4.8 million, or 31 cents. Total revenue was $181.2 million, up from $169.4 million a year prior. For 2012, the insurer recorded operating earnings of $58.1 million, or $3.8 per share, outperforming 2011 results of $13.7 million, or 90 cents. Total annual revenue was $703.9 million, up from $660.2 million.