Average pay? Depends on who and what profession you're referring
to.
Administrative Service officers in the Civil Service typically
receive $3500 as fresh grads (24-25yrs old), and around 6k at 30,
while their clerks probably something like 1-2k.
SAF specialists probably around 2-3k, while SAFOS scholars around
7k for the approx 50% of them who become LTCs at around
30yrs.
Doctors at 30yrs are usually hospital Registrars or
newly-established GPs, taking home around 7-8k.
Teachers... depends. If you're one of those China-imports specially
invited by MOE to teach chinese in schools here, your starting pay
is 4.5k... yes, sounds crazy but true.
Lawyers... also depends. Outstanding ones earn alot, whilst some
quite miserable. 
And not forgetting that if you join PAP and get elected into
parliament, your pay is 13k.
So it all depends.
