Assuming you are talking about [0], the graph looks as if the value of 2009 was taken as reference point and percentages are calculated relative to that. You co

Assuming you are talking about [0], the graph looks as if the value of 2009 was taken as reference point and percentages are calculated relative to that. You could look it up in [1] where the graphics seems to be taken from. [0] https://www.emcdda.europa.eu/media-library/amphetamine-price-and-purity-european-union-updated-june-2021_en https://www.emcdda.europa.eu/media-library/amphetamine-price... [1] https://www.emcdda.europa.eu/publications/edr/trends-developments/2021 https://www.emcdda.europa.eu/publications/edr/trends-develop...