In 1965, there were about 180,000 nuns in America. By 2007, that number dropped to 63,000 with an average age of 70. The average age of the Dominican Sisters of Saint Cecilia of Nashville, TN, is 36. Their numbers have increased so steadily in the past 15 years that they have had to build a 100,000 square-foot addition to the property. R&E visits the order to find out what draws the women…