Here is a question about this article: One wave of the population boom ended abruptly in the mid-1980s, as oil prices fell precipitously. The space industry also suffered in 1986 after the Space Shuttle Challenger disintegrated shortly after launch. There was a cutback in some activities for a period. In the late 1980s, the city's economy suffered from the nationwide recession. After the early 1990s recession, Houston made efforts to diversify its economy by focusing on aerospace and health care/biotechnology, and reduced its dependence on the petroleum industry. Since the increase of oil prices in the 2000s, the petroleum industry has again increased its share of the local economy.
What is the answer to this question: In the 1990's, what is something Houston did to try to diversify it's economy?
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So... reduced its dependence on the petroleum industry

Here is a question about this article: London is a leading global city, with strengths in the arts, commerce, education, entertainment, fashion, finance, healthcare, media, professional services, research and development, tourism, and transport all contributing to its prominence. It is one of the world's leading financial centres and has the fifth-or sixth-largest metropolitan area GDP in the world depending on measurement.[note 3] London is a world cultural capital. It is the world's most-visited city as measured by international arrivals and has the world's largest city airport system measured by passenger traffic. London is one of the world's leading investment destinations, hosting more international retailers and ultra high-net-worth individuals than any other city. London's 43 universities form the largest concentration of higher education institutes in Europe, and a 2014 report placed it first in the world university rankings. According to the report London also ranks first in the world in software, multimedia development and design, and shares first position in technology readiness. In 2012, London became the first city to host the modern Summer Olympic Games three times.
What is the answer to this question: What measurement designates London as the world's most visited city?
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So... international arrivals

Here is a question about this article: The European Central Bank (ECB) is the central bank for the euro and administers monetary policy of the Eurozone, which consists of 19 EU member states and is one of the largest currency areas in the world. It is one of the world's most important central banks and is one of the seven institutions of the European Union (EU) listed in the Treaty on European Union (TEU). The capital stock of the bank is owned by the central banks of all 28 EU member states.[dated info] The Treaty of Amsterdam established the bank in 1998, and it is headquartered in Frankfurt, Germany. As of 2015[update] the President of the ECB is Mario Draghi, former governor of the Bank of Italy, former member of the World Bank, and former managing director of the Goldman Sachs international division (20022005). The bank primarily occupied the Eurotower prior to, and during, the construction of the new headquarters.
What is the answer to this question: What is the official, central bank for the euro?
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So...
The European Central Bank