A much more advanced estimate for The Netherlands was made in 2001 by a collaboration of the National Institute for Public Health and Environment (RIVM), Statistics Netherlands (CBS) and the Institute for Environmental Studies (IVM). The estimate arrived at around 50 percent of the production level, c.q. the national income of The Netherlands. This corresponds with the production level of the beginning of the 1970s. As the population was smaller at that time, the consumption per person was substantially higher than 50 percent of the present level.