A circular disc of radius R carries surface charge density  σ(r)=σ01−rR, where σ0 is a constant, and 𝑟 is the distance from the center of the disc. Electric flux through a large spherical surface that encloses the charged disc completely is ϕ0. Electric flux through another spherical surface of radius R4 and concentric with the disc is ϕ. Then the ratio ϕ0ϕ is_________