[bw.basicstats] good to add MOMM speed and overall coverage

[BiancaMorandi]

Is your feature request related to a problem? Please describe.
The bw.basicstats table just provide info about the mean values but it would be good to add also MOMM stat (seas adjusted) and overall coverage percentage.

[BiancaMorandi]

@stephenholleran I have added this issue as requested on todays clients call.