Multi-column sorting

So the problem is simple enough to explain.  I want to sort the following visual by year and then by quantity:

I want to sort sales into year order. Where two or more sales occur in the same year, I want to sub-sort them by quantity.

Sorting by two columns

The (new) answer is to hold the SHIFT key down when you click on a column header.  Here's how this could work, using the above table as an example.  Firstly, click normally on the Year column:

The data is now sorted by year.

Now hold down the SHIFT key and click on the Quantity column:

Now I can see the data sorted into ascending year order, and within year into descending quantity order.

Hold down the SHIFT key and click on the Quantity column again to change the sort order:

Eureka - this is what I wanted (the data is sorted into ascending year order and ascending quantity order).

Sorting by more than 2 columns

You can hold down the SHIFT key and click on a third column (and presumably a fourth and a fifth ...):

Here I'm sorting by environment, year and quantity.

Reversing the priority of columns

To swap the order of the two columns, hold down the SHIFT key and click on the first sort column (the Year).  This changes the table so that it sorts firstly by quantity and then by year.

Hold down the SHIFT key and click on the Year column, which is being used as the primary sort key.

Here's what this would then show:

The data is now sorted by Quantity and only then by Year (although because the quantities are all unique you'll have to take my word for this).

All very simple and elegant!