The change in water use efficiency over time (CWUE). The change in the ratio of the value added to the volume of water use, over time. Water Use Efficiency (WUE) is defined as the volume of water used divided by the value added of a given major sector . Following ISIC 4 coding, sectors are defined as: 1. agriculture; forestry; fishing (ISIC A), hereinafter “agriculture”; 2. mining and quarrying; manufacturing; electricity, gas, steam and air conditioning supply; constructions (ISIC B, C, D and F), hereinafter “MIMEC”; 3. all the service sectors (ISIC E and ISIC G-T), hereinafter “services”. The unit of the indicator is expressed in Value/Volume, commonly USD/m3. Metadata: https://unstats.un.org/sdgs/metadata/files/Metadata-06-04-01.pdf Source: http://www.fao.org/3/CA1588EN/ca1588en.pdf