You should have read it first prior to pstng
In fact, let me pull this for you:
<quote>
The deceptive nature of fraud makes its extent in the Medicare program difficult to measure in a reliable way, but it is clear that fraud contributes to Medicare's fiscal problems. <strong>More broadly, in fiscal year 2013, CMS estimated that <ul>improper payments—some of which may be fraudulent</ul>—were almost $50 billion.<strong>
<quote>

Improper Payment is NOT 100% fraud. 
Improper payment, in general, means that Medicare paid out for procedure A when it should not have. Of course, a VERY SMALL PORTION of that is fraud. IOW, fraud would be something that was submitted but with lies attached to it or procedures were not actually done. 
BTW, had YOU actually done the real work and understood what is happening, you would have found that GAO PURPOSELY skipped over the portion where procedures were NOT PAID, but should have been. oddly, over/under tend to work in medicare's favor, not the providers.