In 2006, San Diego was rated the very best city (with a populace in excess of one million) for biking in the U.S. In 2011, the town announced plans to upgrade 80% of its street lighting to new vitality-efficient lights that use induction technological know-how, a modified variety of fluorescent lamp developing a broader spectrum than sodium vapor lamps. In the mid-20th century the city experienced mercury vapor street lamps.