Why did Guilford County think they were going to bring in $385,457,668 in property taxes in 2011-12, but adopted a budget saying $358,391,098 in 2012-13?

Guilford County 2012-13 adopted budget

FY 2012-13 Planned Property Tax Revenues - $358,391,098

FY 2013-14 Planned Property Tax Revenues - $403,817,284

Where is the $45,426,186 going to come from next year?

How much is coming from the property revaluation?

Link to 2011-12 Guilford County adopted budget