Top panel: variation of monthly averaged sunspot area data from Kodaikanal with time. Bottom left panel: wavelet power spectrum. Cross-hatched regions above the wavelet power spectrum show the cone of influence (COI). Bottom right-hand panel: global wavelet power. The maximum measurable period is ~33 yr, which is shown by a horizontal dashed line. The dotted line above the global wavelet power plot shows the significance level of 99%. The significant periods as measured from the global wavelet power are printed on the panel.