Who has experience in trading managed account?

[fxtrader777]

I am trading two managed accounts. The system which I follow generates not super high profits but steady 5-10% a month. Also I follow money management rules and I have never used leverage more than 5:1.

I charge 25% from total profits on every month.

I want to ask, Should I charge more? I have been trading this accounts for 13 months.
How much do you usually charge? Provided you bring 5-10% monthly profits

thanks