Organic traffic value is the equivalent monthly cost of traffic from all keywords that the target website/URL ranks for if paid via PPC instead of ranking organically. 

We calculate it based on multiplying the monthly organic traffic of each keyword at the respective ranking position by the CPC value. Then, we add up the organic traffic cost of individual keywords that the target website/URL ranks for. 

In essence, the number gives you a sense of how valuable a domain’s keyword profile is. Another way to think of it is how much money the target website/URL has saved in terms ranking for keywords organically, instead of buying paid traffic. 

Paid traffic value shows the estimated monthly cost of paid search traffic from all the keywords that a target website/URL ranks for via PPC.

We calculate it based on multiplying the monthly paid traffic of a keyword by the CPC value. Then, we add up the paid traffic cost of individual paid keywords.

Go to Site Explorer > Overview 2.0 > Performance Chart > tick the Avg. organic traffic value:

Traffic value history chart shows you the history of your target website's or URL's traffic value, plotted on a graph.

You can choose between the time periods, years, countries, add competitors and export the graph.

A similar history chart is also available for the Average Paid Traffic Cost.