Rainfall depth over a watershed is monitored through six number of well distributed rain gauges. Gauged data are given below

$$\begin{array}{|c|c|} \hline\textbf{Rain Gauge Number} & 1 & 2 & 3 & 4 & 5 & 6 \\ \hline \textbf{Rainfall Depth (mm)} &470 & 465 & 435 & 525 & 480 & 510 \\ \hline \textbf{Area of Thiessen Polygon ($\times 10^4 m^2)$} & 95 & 100 & 98 & 80 & 85 & 92 \\ \hline \end{array}$$

The Thiessen mean value (in mm, up to one decimal place) of the rainfall is _____