FGW run 9500 trains per week, serving 276 stations.
Their trains run 70M miles per annum.
Their trains carry 99.5M passengers per annum.
(Doing the maths shows that every train carries an average of 200 passengers)
For comparison East Coast runs 976 trains per week, and carries 20M passengers per annum Mike Many thanks to Mike Roach for noticing and reporting the above.