Distribution of magnetic field and spin period for 1864 pulsars (data from the ATNF pulsar catalogue, see Manchester et al. 2005). Here, 141 binary pulsars and 13 magnetars (Kouveliotou 2003) are separately identified for the statistics of magnetic field and spin period. The 24 accretion millisecond X-ray pulsars discovered by RXTE (see e.g. Wijnands 2005; Lamb & Yu 2005; Yin et al. 2007) are put in the spin period histogram.