Industry, especially the manufacturing sector, historically was linked to agricultural processing until the 1970s, when the construction of hydroelectric plants and new industrial incentives began to broaden the industrial base. Industry was composed principally of manufacturing and construction. Paraguay had no real mining sector, but the manufacture of construction materials included limited mining activity. Manufacturing and construction in the economy in the late 1980s remained dependent on developments in other sectors, such as agriculture and energy, for their growth. Although industry was becoming more visible in Paraguay in the 1980s, industry's share of GDP actually declined in the 1970s and 1980s because of more rapid growth in agriculture.
Question: When did the industry's share of GDP start to decline?
Answer: in the 1970s