Paper 1 February/March 2022 CHEMISTRY (9701/12) IGCSE

Iodine and propanone react according to the following equation.
${I_2}\left( {aq} \right) + C{H_3}COC{H_3}\left( {aq} \right) \to C{H_3}COC{H_2}I\left( {aq} \right) + HI\left( {aq} \right)$
If the concentration of propanone is increased, keeping the total reaction volume constant, the initial rate of the reaction also increases.
What could be the reason for this?