How to determine non-zero values from a string array?

I have following string array and I am trying to find out which string has value that are not equal to zero. I used str2num but apparently I am missing something here to get it right, any tips?

a = 
    ' 0.5%'
    ' 0.0%'
    ' 0.0%'
    ' 0.0%'
    '16.0%'
    ' 0.5%'
    ' 0.0%'
    ' 2.8%'
    ' 0.0%'
    '11.6%'
    ' 0.5%'
    ' 8.3%'
    ' 0.0%'
    '36.7%'
    '23.2%'
Result should look like above except 0.0% taken out!

Answer 1

[KSSV]

clc; clear all ;
a = { ' 0.5%'
    ' 0.0%'
    ' 0.0%'
    ' 0.0%'
    '16.0%'
    ' 0.5%'
    ' 0.0%'
    ' 2.8%'
    ' 0.0%'
    '11.6%'
    ' 0.5%'
    ' 8.3%'
    ' 0.0%'
    '36.7%'
    '23.2%'} ;
% get strings which are 0
idx = strfind(a, '0.0%');
idx0 = find(not(cellfun('isempty', idx)));
% get indices of non-zeros
iwant = setdiff(1:length(a),idx0) ;
a(iwant)

[Mohammed]

Appreciate your prompt answer!