I'm sure that others created a website that works in a similar way to what you want, so a good Google search or in the WP plugins directory should help you find a way to achieve it.
One of the plugins you could check is User Role Editor. https://wordpress.org/extend/plugins/user-role-editor/Statistics: Posted by Cristián Lávaque — June 17th, 2011, 11:35 pm
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