What year was designated as the International Year of Light by the United Nations?

2015 is the International Year of Light celebrating the discovery of various light-related phenomena. It makes the 1000th anniversary of the publication of the Book of Optics by medieval Arab scholar Ibn al-Haytham in 1015, which was widely read through the the Middle Ages and largely set the stage for our modern theory of optics. It is also the 150th anniversary of Maxwell's classical theory of electromagnetism, and the 100 anniversary of Einstein's General relativity, just to name a few.