Below is a breakdown of actual real-life average speeds you can expect from wireless routers within a reasonable distance, with low interference and small number of simultaneous clients:

802.11b - 2-3 Mbps downstream, up to 5-6 Mbps with some vendor-specific extensions.

802.11g - ~20 Mbps downstream

802.11n - 30-50 Mbps typical, varying greatly depending on configuration, whether it is mixed or N-only network, the number of bonded channels, etc. Specifying a channel, and using 40MHz channels can help achieve 70-80Mbps with some newer routers. Up to 100 Mbps achievable with more expensive commercial equipment with 8x8 arrays, gigabit ports, etc.

802.11ac - 70-100+ Mbps typical, higher speeds possible over short distances without many obstacles, with newer generation 802.11ac routers, and client adapters capable of multiple streams.

Which router are you using ?