For each analyte (TE or OCP) and lake separately, values were normalized to the maximum value, which was set to 1. Then, normalized values of a single element of all lakes were put together, ordered according to their date, and then means covering all values in five-year spans were calculated. Lakes with a higher sedimentation rate had thicker sediment layers per year than those with lower rates. This means, that for the given core length of 1 m, layers from lakes with higher sedimentation rate cover a smaller time period and also yield more data points per five-year period than the latter. Consequently, for the five-year periods not always the same number of points or lakes was covered and sometimes lakes were covered twice. Tables and in the Online Resource 1 provide an overview of data points per five-year period and which lakes were included.