It was probably very small but you need only few greek minters to produce such coins. Greeks were there in capacity as sculptors, engineers and military advisors not as farmers so whatever few greeks were available were used in these things.Hellenic influence does not equal "made by Greeks". No one doubts Hellenic influence on Kushans, but the actual quantity of Greeks in that region (Afghanistan, NW India, etc.) was probably quite small. It is much more likely that these coins were made by Indian artisans in Kushan employ using Greek methods.
May be they trained indians of that region as noticed by a relative debased nature of kushan gold coins as aping can not produce originality.
The very existence of those good ones shows that Kushans were not far behind Romans in the craftsmanship of their coins.
Both Romans and Han Chinese commented on the great wealth of the Kushan Empire. Since the Kushan Empire existed when both the Romans and the Han were at their height, and incredibly wealthy in their own right, the fact that Romans like Bardesanes and Han Chinese like Gan Ying comment on the wealth of the Kushans in noteworthy.
Oh come on kushana gold coins are nowhere near roman gold coins. i am really frustrated as it is quite clear and if we can not agree on this, there is some deep problem.
those quotes are hearsay and based on travels in central asian regions of kushanas not inland land.
Fa hein too called Gupta india very prosperous and with great administration. ofcourse, he is unreliable as per you.