What is the second most widely spoken language in Spain?

Catalan evolved from Vulgar Latin in the 9th century. During the Low Middle Ages it saw a golden age as the literary and dominant language of the Crown of Aragon, and was widely used all over the Mediterranean (it was an official language in Sicily until the 15th century, and in Sardinia until the 17th century). Today, there are about 9 million Catalan speakers in Spain.