Opened_tables value and tweaking table cache
Dived Opened_tables by Uptime to get tables opened per second.  But even that is not very useful.

Much more useful are the 3 values of SHOW GLOBAL STATUS LIKE 'table_open_cache%';  More than a few misses or overflows per second is worth noting.

There are many other metrics; provide the data that Wilson mentioned; see can dig further.

Only one FLUSH TABLES since boot up?  No big deal.

mysqladmin status does not provide much useful info.

Be aware that the values in STATUS have different flavors, has many flavors:


Counters -- monotonically increasing since startup.  In most cases, dividing by Uptime is appropriate.  Eg: Opened_tables; Com_%.
High-water-marks -- eg:  Max_used_connections
Current values -- eg: Threads_running (usually 1, namely the query that is fetching the values)