Time series of measured TSI values. The light blue thin line shows monthly means and yearly averages are denoted by the thick blue curve. This TSI-composite is a version by the author (see text for the merging procedure). Also shown are other TSI-composites: The PMOD TSI-composite (Fröhlich, 2006, thin green line with open green triangles), the composite of Dudok de Wit et al. (2017, red line, open red squares), and the measurements of SORCE/TIM (Kopp et al., 2005, thin gold line, open gold circles). The filled grey circles illustrate a mean over 21-years with the entry plotted at the last year of the interval.