I'm sorry to say that I don't count the sheets. What I can tell you is that I print two pages (B/W and colour) every day and the levels are now half full. The period is between 26.08.15 and about 01.03.15, about 6 months.
For a small business, and a household it is well enough without having to complain. The figures are always a median value, and you don't always need the same amount of toner when printing.
I use it to print invoices, quotations, envelopes, the occasional googlemap or small brochures.