https://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=23392
<<Intel removed this version in their website for unknown reasons>>
A vanilla Google search for "intel proset wireless 16.6" pulls this right up.
Release notes for 16.6: Release Notes for Intel® PROSet/Wireless WiFi Software
Interesting reading here re: 17.12: http://webcache.googleusercontent.com/search?q=cache:Dl5ItoyyH_MJ:ftp://70.35.58.70/Notebook/Intel_WLAN/WLAN_v17.12/Inte…