Consider the following production function that is already written in per worker terms: y = Akαh 1-α where h represents human capital per worker. Suppose we are given the following information: capital per worker in an economy has been growing at 1% per year, human capital per worker has been growing at 5% per year, and output per worker has been increasing at 1% per year. What is the rate of productivity growth? Assume that α = 1/3.