I have set up a bar chart which displays values grouped by finacial year quarter, a nominal attribute. The data is displayed with the x-axis labels in alphabetical order rather than cronological order as they appear in the data, ie Q1 2012, Q1 2013, Q2 2012, Q2 2013 etc, as shown below. I need them to be ordered by year and quarter, such as Q1 2012, Q2 2012, Q1 2013, Q2 2013.
Current ordering of x-axis labels