Observed distribution of jet half-opening angles of 74 long bursts (based on the compilation in Lu et al. 2012) compared to the short-burst sample. Since the latter has much less data, we do not plot a histogram but only points. An arrow indicates a lower limit on Θ_jet. The Type I events GRB 051221A, 060614, and 070714B listed in Lu et al. (2012) have not been used for the plot of the long-burst data.