Cuda 9.1 .deb installer installs cuda 10.1

I am trying to install cuda 9.1 on Ubuntu 16.04. I have tried the .deb(network) and .deb(local) installers, but both of them are installing cuda 10.1.

I would really appreciate any help. I need to get this working as soon as possible.

sudo apt-get install cuda-9-1

https://docs.nvidia.com/cuda/cuda-installation-guide-linux/index.html#package-manager-metas

Thank you, Robert.