This was twice the rate of population growth, but somewhat less than the rate of GDP growth, which increased by an estimated factor of 19, at constant prices, over the twentieth century (De Long, 1998). These statistics therefore present long-run evidence of "relative decoupling" of material extraction from GDP. However, such relative resource decoupling does not entail an absolute reduction in resources used. Indeed, according to this more recent data, since 2000 material extraction appears to have grown at a faster rate than GDP - suggesting the possibility of "recoupling" if this trend persists.