Why debt/equity ratio is limited to between 0 and 9 Is there any economic reason that debt/equity is limited to between 0 and 9 as in the picture below?

This research examines the impact of the law on firms' financial flexibilities.
When a company is in near-bankrupt state, it's equity $\rightarrow0$, meaning that D/E goes $\rightarrow\infty$. Including such observations would make the resulting mean D/E meaningless. This is why boundaries are needed