  Results obtained from an analysis of the energy spectrum of cosmic rays with
energies in the region of $E_0 \ge 10^{17}$ eV over the period of continuous
observations from 1974 to 2017 are presented. A refined expression for
estimating the primary-particle energy is used for individual events. This
expression is derived from calculations aimed at determining the responses of
the ground-based and underground scintillation detectors of the Yakutsk array
for studying extensive air showers (EAS) and performed within the QGSJET01,
QGSJET-II-04, SIBYLL-2.1, and EPOS-LHC models by employing the CORSIKA code
package. The new estimate of $E_0$ is substantially lower than its counterpart
used earlier.
