0.75 g of a sample of pyrolusite ore is treated with 1.89 g of oxalic acid crystals $\left({\text{H}}_{\text{2}}{\text{C}}_{\text{2}}{\text{O}}_{\text{4}}.{\text{2H}}_{\text{2}}\text{O}\right)$ in acidic medium to analyze for its  ${\text{MnO}}_{\text{2}}$ content. Following the reaction, the excess oxalic acid is titrated with 0.100 M ${\text{KMnO}}_{\text{4}}$ under acidic conditions, 30.00 mL being required. The percentage of Mn in the ore is______. (Atomic weights: Mn = 55 u)