Given the task definition and input, reply with output. In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.

Passage: Virginia has the highest concentration of technology workers of any state, and the fourth-highest number of technology workers after California, Texas, and New York. Computer chips became the state's highest-grossing export in 2006, surpassing its traditional top exports of coal and tobacco combined, reaching a total export value of $717 million in 2015. Northern Virginia, once considered the state's dairy capital, now hosts software, communication technology, defense contracting companies, particularly in the Dulles Technology Corridor.
The state has the highest average and peak Internet speeds in the United States, with the third-highest worldwide. Northern Virginia's data centers can carry up to 70% of the nation's Internet traffic, and in 2015 the region was the largest and fastest growing data center market in the nation.Forbes magazine has named Virginia the best state in the nation for business five times, and included it in their top five in 2018, as did CNBC in their America's Top States For Business 2018 rankings, with its deductions being mainly for the high cost of living. Additionally, in 2014 a survey of 12,000 small business owners found Virginia to be one of the most friendly states for small businesses. Virginia has 23 Fortune 500 companies, ranking the state sixth nationwide. Tysons Corner is one of the largest business districts in the nation.
Tourism in Virginia supported an estimated 210,000 jobs and generated $21.2 billion in 2012. Arlington County is the top tourist destination in the state by domestic spending, followed by Fairfax County, Loudoun County, and Virginia Beach.
Computer chips became the highest-grossing export of 2006 for what?