LDO Efficiency calculation parameter
The efficiency is a function of output current, it is not a constant.
So the efficiency of an LDO will, in general, be zero with no load current and maximum at the maximum output current.
So it really depends on at what output load current you want to evaluate the efficiency.

It's not straightforward to come up with a general closed-form solution for efficiency given Iout(t), but if input and output voltages are fixed and your output current is piecewise constant you can simply take a time-weighted average of output current.
For example, Vin = 5.0V, Vout = 3.3V , Iq = 1mA and Iout is 10mA for 10% of the time and 1mA for 90% of the time.
Efficiency with Iout = 10mA is 60%
Efficiency with Iout = 1mA is 33%
Average efficiency is thus 35.7%.