Observations of proper motions of single radio pulsars enable the determination of transverse velocities and hence provide a tool for measuring the amount of asymmetry (i. e., the magnitude of the kick velocity vec{w}) in supernovae (SNe). However, single pulsars are thought to originate from both isolated early type stars which explode in a type II SN and from the collapse of He-stars in a SN of type Ib/c in massive binaries which are disrupted as a result of the explosion. Other, more exotic, formation mechanisms of isolated neutron stars (NS) include the possibility of accretion-induced collapse (AIC) of a white dwarf (WD) and a merging event of two white dwarfs in a very tight binary system (possibly resulting in a type Ia SN). It is therefore complicated to get a direct measure of the magnitude of kick velocities imparted to neutron stars at birth. ...