[X/Fe] ratios of the elements with Z≤ 30 as a function of stellar ages for the nine solar twins analyzed here (circles). We also plotted the measurements taken from the literature as triangles. The red triangles represent the thick disk stars. The [X/Fe]-age distributions have been fitted by linear, hyperbolic and two-segmented line functions showed as blue dashed, red solid and green dashed lines, respectively. The parameters related to these functions are listed in Table 2. Note that the y-axes ranges are different from element to element, in order to properly visualize our entire data set.