In a major boost to Boston’s economy, Mayor Thomas M. Menino and state officials today announced that Liberty Mutual plans to grow its global headquarters in Boston, creating 1,100 new jobs and generating more than $50 million in new tax revenue for the City. The company, founded in Boston in 1912, had opportunities to expand in other parts of the country, but ultimately decided that Boston provides the best opportunity for its growth. Liberty Mutual’s anticipated total investment of approximately $300 million in its corporate headquarters would make Boston one of the largest insurance hubs in the country.