The second half of the twentieth century saw rapid growth of outdoor education in all sectors (state, voluntary, and commercial) with an ever-widening range of client groups and applications. In this period Outward Bound spread to over 40 countries, including the US in the 1960s. Other US based outdoor education programs include Project Adventure and the National Outdoor Leadership School (NOLS). Project Adventure focuses on day use of ropes courses. NOLS uses the outdoor setting to train leaders for outdoor programs and for other settings including training every new US astronaut and 10% of the US Naval Academy. The Association for Experiential Education is a professional association for "experiential" educators. The Wilderness Education Association (WEA) is a consortium of college outdoor education programs with a standard curriculum based on an academic model. (See also North America in the Around the World section.)