How U.S tech companies evolved as most valuable among other U.S companies past 100 years ?

According to stats by Forbes, here are the top 10 largest U.S companies in years from 1917 , 1967 and now in 2017. Tech companies surpassed the other companies to become most valuable companies. Apple is at the helm with valuation $898 billion followed by Alphabet $719 billion.

Source: howmuch.net

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RVD