Measurements of the galactic cosmic ray intensity for energies E>2 GeV and E>60 MeV near earth and for E>60 MeV at 52 GeV during 1955--1965 and 1965--1977 can be simulated by the accumulative effects of Forbush decreases, and (4) there is a difference in the energy dependence of decrease and recovery phases of the 11-year variation. These results clearly indicate that a time-dependent solution to the cosmic ray transport equation is required to describe the solar cosmic ray modulation.