Can not determine scale of x-axis of attached graph

38 Views Asked by At

I am trying to digitize the data from the graph in this link.

I thought the $x$-axis was in $\log_{10}$ scale but after trying to digitize this way the points seemed off. I also tried digitizing in $\log_2$ but again failed.

Can anyone help to determine what scale the $x$-axis is in?