All of our VRDs are written with real world testing to back them up. We have not refreshed this VRD and have not completed all of the testing to have the 3 stream numbers.
The VRD is written with 2x2 MIMO in mind. In this particular graphic all of the clients were two stream clients. There has been signifcant growth in single stream clients (laptops and tablets). My recommendation would be to use the 2 stream numbers since the 3 stream and 1 stream clients should roughly average out.