Thanks to Kite159's stations spreadsheet, I have some numbers finally!
National Network: 1,494 out of 2,544
LU: 154 out of 255
DLR and Tramlink: 62 out of 84
Light rail empires:
Blackpool: 0/37 (that number is to change most significantly by 192 hours' time

)
Edinburgh: 15/16 (just waiting on Edinburgh Gateway now)
SPT Subway: 15/15
Metrolink: 51/91 (yes it is planned to absolutely smash my way through the list of requirements by the end of the year. Stay tuned...

)
Midland Metro: 23/23
NET: 23/23 (until the new lines open soon, and yes that is planned to be dealt with before the end of the year too. An epic trip is in the works, details to be announced in October

)
Supertram: 21/48
Tyne and Wear Metro: 42/60
The epic trip hinted above is very much in the planning stages, once I come back from Ireland in September I will have it all worked out. It might not be until December, but it is more likely to be November. All will depend on the work situation and holiday time!