Profit Charts - Add Feature

Hi, 

I think it would be beneficial to add a feature to the profit charts that shows another line with the return based on any invested amount of currency. Say you invested $500 and this is how much it would be worth now over the selected time period. This could be an adjustable amount. 

Obviously for most this isn't difficult to work out using the profit % indicator, however I think for the general public it may be beneficial to see as an option in the charts.

Thanks