At the end of the 18th century, approximately percent of the american people earned a major portion of their income by farming.

Right answer is (this is sure):

At the end of the 18th century, approximately 90% percent of the American people earned a major portion of their income by farming.

Explanation:

The US population was nearly 4 million in 1790. 90% of them made a living in agriculture.  That means that post-revolutionary America was an eminently agrarian country.  

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