删除谷歌图表中hAxis之间的空格

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

function drawChart() {
  var data = new google.visualization.DataTable();
  data.addColumn('string', 'Year');
  data.addColumn('number', 'Sales');
  data.addRows([
    ['2015', 1000],
    ['2016', 1170],
    ['2017', 660],
    ['2018', 1030]
  ]);

  var options = {
    hAxis: {
      textStyle: {
        fontSize: 0
      }
    }
  };

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