"increased by 500 percent"

[Joel S. Berson]

In the New Yorker for April 13, Jill Lepore wrote (p. 40, col. 1)
"Between 1790 and 1830, the city's [New York's] population increased
by more than five hundred percent."

Did she mean by a factor of (that is, multiplied by) five, or
six?  (Rhetorical question.)

Joel

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