What is the probability of seeing a neutron star as a pulsar?
Out of 100 pulsars, how many will have a beam that crosses the Earth?


About twelve. 

"The beaming fraction f , that is the mean value of the fraction of observable pulsars or the mean probability of observing a normal pulsar, is 0.124 ± 0.004." M. Kolonko et al.: On the pulse-width statistics in radio pulsars