Citrus canker continues to be an issue of concern. From 1997 to 2013, the growing of citrus trees has declined 25%, from to . Citrus greening disease is incurable. A study states that it has caused the loss of $4.5 billion between 2006 and 2012. , it was the major agricultural concern. The largest farm category by sales in Florida is the $2.3 billion ornamental industry, which includes nursery, greenhouse, flowers, and sod products. Other products include sugarcane, strawberries, tomatoes and celery. The state is the largest producer of sweet corn and green beans for the U.S. The Everglades Agricultural Area is a major center for agriculture. The environmental impact of agriculture, especially water pollution, is a major issue in Florida today. In 2009, fishing was a $6 billion industry, employing 60,000 jobs for sports and commercial purposes. The state has a near monopoly on saw palmetto berries, an alternative medicine used to treat prostate and urinary disorders. Florida is the leading state for sales of powerboats. Boats sales totaled $1.96 billion in 2013. Phosphate mining, concentrated in the Bone Valley, is the state's third-largest industry. The state produces about 75% of the phosphate required by farmers in the United States and 25% of the world supply, with about 95% used for agriculture (90% for fertilizer and 5% for livestock feed supplements) and 5% used for other products. After the watershed events of Hurricane Andrew in 1992, Florida began investing in economic development through the Office of Trade, Tourism, and Economic Development. Governor Jeb Bush realized that watershed events such as Andrew negatively impacted Florida's backbone industry of tourism severely. The office was directed to target Medical/Bio-Sciences among others. Three years later, The Scripps Research Institute (TSRI) announced it had chosen Florida for its newest expansion. In 2003, TSRI announced plans to establish a major science center in Palm Beach, a facility on , which TSRI planned to occupy in 2006. Since the development of the federal NASA Merritt Island launch sites on Cape Canaveral (most notably Kennedy Space Center) in 1962, Florida has developed a sizable aerospace industry. Another major economic engine in Florida is the United States military. There are 24 military bases in the state, housing three Unified Combatant Commands; United States Central Command in Tampa, United States Southern Command in Doral, and United States Special Operations Command in Tampa.