I have done numerous time studies in the work place and this 208,333 coins per year seems quite doable.
Say you work 50 weeks a year and you are actually working 7 hours a day leaving one hour for breaks and what not.
That is essentially 30 seconds a coin.
Estimates are 6 - 10 seconds per coin. By my math this employee is capable of producing at least triple the amount of coins if managed and supported properly. 600,000 - 1,000,000 coins per year.
As a supervisor I am thinking I am under tasking this employee and need to find the bottleneck and squash it.