The index value of this sector is based on a combination of payroll employment and board feet of lumber production at major county lumber companies and is adjusted to account for normal seasonal variations. Lumber-based manufacturing generates about 55 percent of total county manufacturing employment ... The Lumber-based Manufacturing index has been on a downward march and continues to an all time low of 30.7 -- a decline from last month of 18.2%. This index has proved to be a constant weight on the overall composite by continually falling since July.