How often do supernova explosions need to occur to supply the energy of galactic cosmic rays?

To maintain the observed energy levels of galactic cosmic rays, supernova explosions must occur approximately every 50 years within the galaxy.12

Galactic cosmic rays have an average life of about 15 million years and require replenishment at an average power level of roughly ${10}^{41}$ ergs per second to remain at observed intensities. It is widely accepted that the expanding shock waves from supernova explosions provide the necessary power for this acceleration. While the specific details of these acceleration processes remain a subject of ongoing study, supernova remnants are confirmed as significant sources of cosmic rays, capable of accelerating particles to energies ranging from ${10}^9$ to ${10}^{15}$ electron volts.123