We compared this with the cloud depletion time, $\tau_\mathrm{GMA}$, calculated using the GMAs' surface densities, $\Sigma$, cloud radii, $R$, and the star formation surface densities. Fig.~\ref{tdep3} and Fig.~\ref{tdep4} display the results, and Table \ref{tdep_means} also presents the average cloud depletion times and standard errors for each population. Here $\tau_\mathrm{GMA}$ increases with $\Sigma$ and $\sigma_0$ and, though there is little statistical difference in average between populations, $\tau_\mathrm{GMA}$ also increases from nuclear to arm to inter-arm clouds.