Particle yield ratios (\kst $+$ \kstba)$/$(K$^{+}$ $+$ K$^{-}$) in panel (a) and (2\pha)$/$(K$^{+}$ $+$ K$^{-}$) in panel (b), both as a function of \pt for centrality classes 0--10\% and 70--80\% in \pb collisions at \snn $=$ 5.02 TeV. For comparison, the corresponding ratios are also shown for inelastic pp collisions at \s $=$ 5.02 TeV. The statistical uncertainties are shown as bars and systematic uncertainties are shown as boxes. In the text (\kst $+$ \kstba), (K$^{+}$ $+$ K$^{-}$) are denoted by \kst and K, respectively.