Hello,
In my experience, these are the points that have helped me ask (and get a promotion):
• Depending on the positioning of the content (TOFU, BOFU, MOFU), look for - the number of views, number of website visitors, MQLs generated, SQLs, and final conversions.
• If your content is part of various campaigns - see what results those campaigns brought and showcase them separately.
• Think about what will help your manager in achieving their goals. If you can help them get a raise, they will probably give you a raise too!
I am not sure about the number. Generally, I let them offer a raise and then discuss if it fits my expectations. Might be different for different organizations, though.
Hope this helps! :)