What is an average download speed if your connection is at 1 Mbps? I know it varies.?

We think we are having problems with our internet. We have 1Mbp connection but when my son downloads a game the speed says under 100 KB/s usually around 50. why is not more closer to the 1 MBp that we pay for. Is this speed normal? What actuall download speeds do others get/ Thanks for any help.