I noticed under Caching Overview > Cache performance that my site is 50% served by Cloudflare and 50% served by origin.
My website is built on WordPress. Majority of the missed cache are requests in the /wp-content/* directory.
Wanting to improve this (i.e., increase percentage served by Cloudflare), I created the following cache rule below, with an Edge TTL of 7 days and a browser TTL of 1 day.