Here is some data for a cohort of 400 individuals of a species whose abundance was tracked for 6 years (its maximum lifespan). For one-year age intervals from birth to 6 years, you have the following numbers of survivors, 400, 200, 100, 40, 20, 10, and 0. The corresponding per capita birth rates are 0.1, 2.0, 3.0, 4.0, 4.0, 3.0 , and 0.0. What is the basic reproductive rate R0?