I have got a site on CF where the percent cached is 14%.
This site was cloned from another site I have and that was has a cache of around 90%. Have checked all settings in IIS and web.config, but there are no other settings for caching in there.
Compared both sites in CF and all settings are the same. Also purged cache, but it just sits at around 14%.
Your resources seem to be all cached, however your main document is not. Is it supposed to? If so, your server is probably sending some headers which prevent Cloudflare from caching.
The main HTML document, the one at root. Currently its caching status is BYPASS, so you either configured some page rule on Cloudflare or one of your headers tells Cloudflare not to cache.
The latter you need to check yourself, particularly pay attention to caching headers. For the former, post a screenshot of your page rules.
If you felt more comfortable sharing the IP in private, you could also run a check with it at sitemeer.com and then post the time here, so I can dig it out.
Might be also related to the other resources, however on the first site it did appear as if most resources were cached anyhow. You could check this yourself and browse your site to check which resources are returned from the cache and which arent. That might shed some light.