The Sixth District Court of Appeals, in a decision certified for publication, held that the principles that had been set forth in Fuentes remained the proper means by which apportionment should be calculated.  Specifically, the Court held that apportionment should be addressed by subtracting the percentage of permanent disability attributable to pre-existing conditions or otherwise non-industrial causation from an applicant's overall level of permanent disability.  In reaching their conclusion, the Court reasoned that the clear language of L.C. §§ 4663 and 4664 provided for such apportionment and the legislature had expressed no intent to change the calculation of apportionment that had been set forth in Fuentes thirty years ago.