My hourly fee was $1000 because I felt I was worth that much and I had patients fly from Portugal and elsewhere to visit me.
Otherwise the $100 one charges per hour in 2018 will be worth about $98 in 2019 and therefore your real rate will be lower next year if you do not match the inflation.
If you have a fully booked practice you should increase your rate by 10% to 20% a year at the minimum. This is the easiest way to increase your income. Your expenses remain the same and the extra income is profit.
I recommend you invest the extra income in Exchange Traded Fund. Do not invest it in managed mutual funds however as up to 70% of the interest you receive will be taken by the management fees and taxes.
And as always do not forget to give 10% of your income to charity.