Linear fit of the abundance ratios [X/Fe] versus age for all 20 elements. The stars represented by blue crosses are from the thick disk and were not considered in the linear fit (red dashed line). The black empty circles are stars from the distinct population identified in the [Na/Fe] plot, and the blue filled circles and black diamonds are stars from the Cu-rich and Cu-poor populations, respectively. The bottom panel shows the residuals, as well as their average and standard deviation.