Bar chart top axes and bottom axes identical

[Matt Bradley-Roberts]

I'm looking to get the hAxis information I currently have to display both on the top and bottom of a bar char (as it could be a large chart!)

The chart currently looks like this (the data is fake by the way! The labels on the side have been 'redacted'):

Essentially I just want the -2m to +2m labels to show on the top as well.

Here's the code:

var chartHeight = (data.getNumberOfRows() * 20) + 100;

                var options = {

                    height: chartHeight,

                    titlePosition: 'none',

                    chartArea: {width: '50%', height: chartHeight-60},

                    bar: {groupWidth: "75%"},

                    isStacked: true,

                    fontSize: 12,

                    legend: { position: "none" },

                    hAxis: {

                      title: '{!$amount} ({!selectedCurrency})',

                      viewWindow: {

                        min: {!minVal},

                        max: {!maxVal}

                      },

                      ticks: [{!minVal},-{!tick},0,{!tick},{!maxVal}]

                    }

                };

I've attempted to use multiple series, but as there is only one data series, with negative and positive figures, it didn't seem to work. I may be overcomplicating this, so all suggestions welcome!