Shaun its impossible to give a clearcut answer as it depends on the field size.
i.e.in a 12 horse field
TAB 1 = 16.4 %
TAB 2 = 13 %
TAB 3 =11.7 %
TAB 4 = 11.0 %
TAB 5 = 10.4 %.

Now contrast that with a 10 horse field.
TAB 1 =17.7 %
TAB 2 = 16.7%
TAB 3 = 12.8 %
TAB 4 = 11.7 %
TAB 5 = 9.9 %.
Hope thats of some help.
Cheers.
Darky.