Metal deficiency defect is shown by $\mathrm{Fe}_{e 0.93} \mathrm{O}$. In the crystal, some $\mathrm{Fe}^{2+}$ cations are missing and loss of positive charge is compensated by the presence of $\mathrm{Fe}^{3+}$ ions. The percentage of $\mathrm{Fe} 2+$ ions in the $\mathrm{Fe}_{0.93 \mathrm{O}}$ crystals is $\_\_\_\_$ (Nearest integer)