Running mean of the abundance ratios of phosphorus to odd-Z (Na, Al, and K in the left panels) and even-Z (Mg, Si, and S in the right panels) as a function of [Fe/H]. The running mean and standard deviation are shown with the blue line and blue band, respectively. The mean value, ([P/X]> (excluding the two s-rich stars), is denoted in the bottom right part of each panel. Horizontal dash-dotted lines represent [P/X] values of ±0.15 dex.