A vertical stoping block of length 60.0 m, height 40.0 m, and average width 1.5 m has sharp boundary walls. However, the mining width of the stoping block is 2.0 m. The tonnage factors are 3.0 tonne/m³ for ore and 2.5 tonne/m³ for wall rocks. The average grade of ore is 10.0%. The overall grade of ore mined on account of dilution in percentage is ______ (round off to 2 decimal places).