Frequencies for psi_90_safety_ratestr variable in vwhqi_hosp_ahrq dataset :

PSI_90_SAFETY |
        _RATE |      Freq.     Percent        Cum.
--------------+-----------------------------------
              |        159        3.29        3.29
Not Available |      4,671       96.71      100.00
--------------+-----------------------------------
        Total |      4,830      100.00

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