13px yui grid values:

 1px    0.077
 2px    0.154
 3px    0.231
 4px    0.308
 5px    0.385
 6px    0.462
 7px    0.538
 8px    0.615
 9px    0.692
10px    0.769
11px    0.846
12px    0.923
13px    1.000

16px    1.231

180px   13.846
220px   16.923
240px   18.462
300px   23.077
360px   27.692

600px   46.154
640px   49.231
720px   55.385
740px   56.923
840px   64.615
900px   69.231
950px   73.077
960px   73.846