饼状图，在成本标签后面加上百分数，电成本 81.69%，气成本，水成本一样。求指教！谢谢！

option = {
toolbox: {
feature: {
saveAsImage: {show: true}
}
},
tooltip : {
trigger: ‘item’,
formatter: “{b} : {c} ({d}%)”
},
legend: {
bottom: 10,
left: ‘center’,
data: [‘电成本’,‘气成本’,‘水成本’]
},
series : [
{
type: ‘pie’,
// 大小，位置
radius : ‘50%’,
center: [‘50%’, ‘50%’],
data:[
{value:${dian}, name: ‘电成本’},
{value:${qi}, name: ‘气成本’},
{value:${shui}, name: ‘水成本’},
],
}
]
};