Regarding skew from clock Report

Hi all,,,

 Nr. of Subtrees                : 118
Nr. of Sinks                   : 18810
Nr. of Buffer                  : 3231
Nr. of Level (including gates) : 23
Root Rise Input Tran           : 100(ps)
Root Fall Input Tran           : 100(ps)
Max trig. edge delay at sink(R): tri_des_B/des3/u2/L10_reg_14_/CK 2192.4(ps)
Min trig. edge delay at sink(R): ahbSlaveIF/readData_sel_reg/CK 2025.9(ps)

                                 (Actual)               (Required)
Rise Phase Delay               : 2025.9~2192.4(ps)      0~1000(ps)
Fall Phase Delay               : 2076.3~2257.4(ps)      0~1000(ps)
Trig. Edge Skew                : 166.5(ps)              100(ps)
Rise Skew                      : 166.5(ps)
Fall Skew                      : 181.1(ps)
Max. Rise Buffer Tran          : 304.4(ps)              300(ps)
Max. Fall Buffer Tran          : 317.4(ps)              300(ps)
Max. Rise Sink Tran            : 388.4(ps)              100(ps)
Max. Fall Sink Tran            : 405.2(ps)              100(ps)
Min. Rise Buffer Tran          : 25.9(ps)               0(ps)
Min. Fall Buffer Tran          : 25.1(ps)               0(ps)
Min. Rise Sink Tran            : 15.3(ps)               0(ps)               
Min. Fall Sink Tran            : 14.4(ps)               0(ps)
    
view cipher_func_mode_rcworst_corner_view : skew = 166.5ps (required = 100ps)
view cipher_func_mode_rcbest_corner_view : skew = 76.4ps (required = 100ps)

Can any explain the skew of my design from report?