tooltip: {
                trigger: 'axis', 
                showDelay: 0, 
                backgroundColor: 'rgba(0,0,0,0.55)',
                padding: [10,70], 
                formatter : '{b}年<br/>满意度 : {c}%',
                axisPointer: { 
                    type: 'line', 
                    lineStyle: { 
                        color: '#dddddd',
                        width: 1,
                        type: 'dashed'
                    },
                },
                textStyle: {
                    color: '#fff'
                }
            },