One way to do this is using a dual axis chart. If you are not familiar with that, you might look at this quick start: http://downloads.tableausoftware.com/quickstart/feature-guides/combo_charts.pdf
And, there is a thread here in which I give details on using dual axes: http://community.tableau.com/message/200579?tstart=0
I've attached a workbook which demonstrates using your data. Please let me know if you have any questions!
Total Lines.twbx.zip 23.1 KB
Thank you so much! I tried Dual axes earlier, but didn't realise I could manipulate the "color" separately on each axis