How many shipyards are there in Zhoushan?

I am from Zhoushan, and there are many Zhoushan shipyards, including shenjiamen, Dinghai, Daishan, Qushan, Putuo, Liu Heng and Daju. How can n be more than 20? Nanyang Shipyard Cizi Shipyard Zhenghe Shipyard Dafang Shipyard Cizi Dinghai Ligang Xingzhou Shipyard Zhejiang Hongzhou Shipyard Co., Ltd. Zhoushan Ligang Shipyard Co., Ltd. Zhoushan Zhou Jin Shipyard Dinghai Pan Zhi Shipyard Zhoushan Haichen Shipbuilding Engineering Co., Ltd. Zhoushan Zheng Tai Shipbuilding Industry Co., Ltd. Yuanhang Group shenjiamen Jiangwan Shipyard, Zhoushan Shipyard and Ant Island East Coast Shipyard Co., Ltd., Wuzhou Shipyard Zhejiang Ling Kai Shipyard Yanchang Shipyard, Maozhi Shipyard, Gan Lan Shipyard, Sanjiang Shipyard, Changzhi Shipyard Yihai Shipyard Zhoushan Xinya Shipyard Co., Ltd., Zhejiang Ou Hua Shipyard Wanbang Yongyue Shipyard Putuo Longshan Shipyard Luomen Yuheng Shipyard COSCO Zhoushan Shipyard Zhoushan Putuo Dong Peng Shipyard Co., Ltd. Zhoushan Yuan Ye Shipyard Co., Ltd. Zhejiang Zhoushan Golden Bay Shipyard Korea Hanjin Shipping and Qingdao Shunhe Shipping Cooperation Xiushan Changshi Group Daishan Haizhou Shipyard Co., Ltd.