Frequencies for psi_12_postop_pulmemb_dvt variable in vwhqi_hosp_ahrq dataset :

           PSI_12_POSTOP_PULMEMB_DVT |      Freq.     Percent        Cum.
-------------------------------------+-----------------------------------
      Better than U.S. National Rate |         81        1.79        1.79
No Different than U.S. National Rate |      2,872       63.57       65.36
                       Not Available |      1,291       28.57       93.94
           Number of Cases Too Small |        105        2.32       96.26
       Worse than U.S. National Rate |        169        3.74      100.00
-------------------------------------+-----------------------------------
                               Total |      4,518      100.00

by Jean Roth , jroth@nber.org , 16 Nov 2016