As Rayna suggests, there's just not the stats available. Besides which they really would not have any meaning when presented as one 'lump of data'
If you have an interest in the refusal rate at the Manila Hub for settlement type visa's submitted from the Philippines alone
I can tell you it's 10% during 2012/2013
Between 2008 - 2011 the average annual refusal rate was 8%
There was a 'bit of a blip' during July 2012 which was likely caused by some folks not having a good understanding of the new immigration rules. The increase in refusal rate is almost certainly due to lack of experience in meeting the new Financial Requirements. It must be stated though that small clarifications/changes/allowances in the rules during the past few months have made a slight improvements in covering more examples of peoples earning differences. (eg Salaried Employment v non-Salaried Employment)
These days a "zero-hours" contract is getting more common and until the recent changes all but impossible to precisely fit into the UKBA 'Financial Puzzle'