Sales of wine have fallen - 30％ in the last ten years .A、on

Sales of wine have fallen _by_ 30％ in the last ten years .A.on B.by C.to
过去的十年里,酒的销售量下降了30%.to表示“到”,后接终值,by表示“增/减”量,为原值和终值的差值或比值（%）