为v轴google图表添加后缀

google.charts.load('current', {packages: ['corechart']});
google.charts.setOnLoadCallback(drawChart);

function drawChart() {
  var data = google.visualization.arrayToDataTable([
    ['Year', 'Sales'],
    ['2015', 100],
    ['2016', 150],
    ['2017', 200],
    ['2018', 250]
  ]);

  var options = {
    vAxis: {
      format: '###%' // 设置百分号后缀
    }
  };

  var chart = new google.visualization.LineChart(document.getElementById('chart_div'));
  chart.draw(data, options);
}