MDL: create a new waveform and save it into a wavefile

Hello,

I have this MDL file:

alias measurement mdltest { 

run tran
print fmt("%g %g\n", xval(voutp), yval(voutp)) addto="sample.txt"
export real divided = V(voutp) / V(voutn)

}

run mdltest

and I run it with this command:

spectre =mdl main.mdl input.scs

During the simulation, a sample.txt file is created and the X and Y values of the signal are periodically written to it, as expected (it is important that I do not have to wait for the simulation to end).
I would expect the wave file, called mdltest.meas_tran (in this context), to contain a signal called "divided" and this signal should be the ratio of voutp and voutn at every time step of this transient simulation.

Instead, I have a signal which has only a single point of data. Why is this happening? The reference manual is not very clear on how to generate and plot a new signal from an expression.

Thank you and best regards,

Patrik