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The cosmic ray 11-year variation for solar cycle 20 is attributed to the modulating effect of solar flare-induced shocks propagating through the interplanetary medium to the boundary of the heliosphere. The relative influence of these disturbances upon the cosmic ray intensity as a function of their travel time from the Sun is determined by a deconvolution of a linear system with the number of solar flares (importance ≥1) and the observed cosmic ray intensity as the input and output respectively of this system. The 'impulse response function' so determined indicates that the solar flare - induced disturbances significantly modulate cosmic rays out to a distance of 70-90 AU where the modulating effect of the disturbances abruptly ends. This is interpreted as the boundary of the heliosphere. [ABSTRACT FROM AUTHOR] more...