JOINT FILING AGREEMENT
In accordance with Rule 13d-1(k) (l) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree to the joint filing of the attached Schedule 13G, and any and all amendments thereto, and expressly authorize Invesco Ltd., as the ultimate parent company of each of its undersigned subsidiaries, to file such Schedule 13G, and any and all amendments thereto, on behalf of each of them.
Dated: 12/31/2011
Invesco Ltd.
By: /s/ Lisa Brinkley
Name: Lisa Brinkley
Title: Global Assurance Officer
Invesco Advisers, Inc.
By: /s/ Jeffrey Kupor
Name: Jeffrey Kupor
Title: Senior Vice President
Invesco Canada Ltd.
By: /s/ Wayne Bolton
Name: Wayne Bolton
Title: Vice President, Compliance & Chief Compliance Officer
Invesco National Trust Company
By: /s/ Kevin Lyman
Name: Kevin Lyman
Title: Assistant General Counsel
Invesco Hong Kong Limited
By: /s/ Asha Balachandra
Name: Asha Balachandra
Title: Reg. Head of Legal AP
Invesco Asset Management Deutschland GmbH
By: /s/ Stephanie Ehrenfried
Name: Stephanie Ehrenfried
Title: Head of Legal CE
Invesco Asset Management Limited
By: /s/ Nick Styman
Name: Nick Styman
Title: Director of European Compliance
Invesco Asset Management S.A.
By: /s/ Nicolas Bouet
Name: Nicolas Bouet
Title: Deputy Managing Director
Invesco Asset Management S.A.
By: /s/ Bernard Aybran
Name: Bernard Aybran
Title: Deputy Managing Director
Invesco Asset Management Oesterreich GmbH
By: /s/ Thomas Kraus
Name: Thomas Kraus
Title: Head of Sales
Invesco GT Management Company S.A.
By: /s/ Nick Styman
Name: Nick Styman
Title: Director of European Compliance
Invesco Management S.A.
By: /s/ John Rowland
Name: John Rowland
Title: Director
Invesco Taiwan Limited
By: /s/ Asha Balachandra
Name: Asha Balachandra
Title: Reg. Head of Legal, AP
Invesco Asset Management (Japan) Limited
By: /s/ Asha Balachandra
Name: Asha Balachandra
Title: Reg. Head of Legal, AP
Invesco Asset Management Ireland Limited
By: /s/ John Rowland
Name: John Rowland
Title: Director
Invesco Kapitalanlagegesellschaft GmbH
By: /s/ Stephanie Ehrenfried
Name: Stephanie Ehrenfried
Title: Head of Legal CE
Invesco PowerShares Capital Management LLC
By: /s/ Deanna Marotz
Name: Deanna Marotz
Title: Chief Compliance Officer
Stein Roe Investment Counsel, Inc.
By: /s/ Greg Campbell
Name: Greg Campbell
Title: General Counsel
Invesco Investment Advisers, LLC
By: /s/ Christopher C. Joe
Name: Christopher C. Joe
Title: Chief Compliance Officer