  Based on electron-positron collision data collected with the BESIII detector
operating at the Beijing Electron Positron Collider II storage rings, the value
of $R\equiv\sigma(e^{+}e^{-}\to$hadrons)/$\sigma(e^{+}e^{-}\to\mu^{+}\mu^{-})$
is measured at 14 center-of-mass energies from 2.2324 to 3.6710 GeV. The
resulting uncertainties are less than $3.0\%$, and are dominated by systematic
uncertainties.
