Which version of CUDA I should download?

My system:
GTX 1050Ti
Driver version:389.04
NVCUDA.dll : NVIDIA CUDA 9.1.188 driver

Some people say I should download CUDA 9, but I only find 8.1 and 10 in NVIDIA website.
Who can help me?

(I am from China and my Engligh is no very good, so there may are some sentences can not be describe accurately. sorry.)