Quickest I could find compares RAW with the major cable networks in regards to viewership and prime-time.
According to Forbes, WWE's drop for RAW in 2016-2017 was 17.6% for the 1st half the year (Jan-June 2016, Jan-June 2017). Last year it was around 9.6% overall based on some quick math. Major cable networks averaged around an 8% drop overall last year with FOX and NFL contributing a lot to the hit.
https://www.forbes.com/sites/alfredk.../#68e6c89577a0
https://www.thewrap.com/broadcast-tv...bs-abc-fox-cw/
http://money.cnn.com/2017/10/26/medi...rks/index.html
http://www.wrestling-online.com/wwe/...t-raw-ratings/