growth, 3.6 percent. The government also implemented a policy of import substitution industrialization, attempting to produce imported goods domestically. The policy promoted the development of textile, food, and other labor-intensive industries in the 1950s and continued into the next decade. As the Chinese Civil War continued without truce, the government built up military fortifications throughout Taiwan. Within this effort, veterans built the now famous Central Cross-Island Highway through the Taroko Gorge in the 1950s. During the Second Taiwan Strait Crisis in 1958, Taiwan's landscape saw Nike Hercules missiles added, with the formation of missile batteries throughout the island. The two sides would continue to engage in sporadic military clashes with seldom publicized details well into the 1960s on the China coastal islands with an unknown number of night raids. During the 1960s and 1970s, the ROC maintained an authoritarian, single-party government under the Kuomintang's Dang Guo system while its economy became industrialized and technology-oriented. This rapid economic growth, known as the Taiwan Miracle, occurred following a strategy of prioritizing agriculture, light industries, and heavy industries in that order. Export-oriented industrialization was achieved by tax rebate for exports, removal of import restriction, moving from multiple exchange rate to single exchange rate system, and depreciation of the New Taiwan dollar. Infrastructure projects such as the Sun Yat-sen Freeway, Taoyuan International Airport, Taichung Harbor, and Jinshan Nuclear Power Plant were launched, while the rise of steel, petrochemical, and shipbuilding industries in southern Taiwan saw the transformation of Kaohsiung into a special municipality on par with Taipei. In the 1970s, Taiwan became the second fastest growing economy in Asia after Japan. Real growth in GDP averaged over 10 percent during the decade. In 1978, the combination of tax incentives and a cheap, well-trained labor force attracted investments of over $1.9 billion from overseas Chinese, the United States, and Japan, especially in the manufacturing of electrical and electronic products. By 1980, foreign trade reached $39 billion per year and generated a surplus of $46.5 million, while the income ratio of the highest to the lowest 20 percent of wage earners dropped from 15:1 to 4:1 between 1952 and 1978, less than even that of the United States. Along with Hong Kong, Singapore, and South Korea, Taiwan became known as one of the Four Asian Tigers. Because of the Cold War, most Western nations and the United Nations regarded the ROC as the sole legitimate government