Observational evidence of solar cycle asymmetry in terms of rise and decay times. Top panel: scatter plots of the ratio $\frac{T_{\mathrm{rise}}}{T_{\mathrm{decay}}}$ versus cycle number, obtained from the sunspot number data. Bottom panel: scatter plots of $\frac{T_{\mathrm{rise}}}{T_{\mathrm{decay}}}$ versus cycle periodicity based on the sunspot number data. The corresponding cycle numbers are annotated in blue in each scatter plot.