Form: SC 13G

Schedule filed to report acquisition of beneficial ownership of 5% or more of a class of equity securities by passive investors and certain institutions

February 14, 2007

JOINT FILING AGREEMENT

Published on February 14, 2007


EXHIBIT A

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
AMVESCAP PLC, 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: February 14, 2007 AMVESCAP PLC


By: /s/ Lisa Brinkley
------------------------------------
Name: Lisa Brinkley
Title: SVP/Global Compliance Director


AIM Advisors, Inc.


By: /s/ Todd L. Spillane
------------------------------------
Name: Todd L. Spillane
Title: Chief Compliance Officer


AIM Capital Management, Inc.


By: /s/ Todd L. Spillane
------------------------------------
Name: Todd L. Spillane
Title: Chief Compliance Officer


AIM Funds Management, Inc.


By: /s/ Wayne Bolton
------------------------------------
Name: Wayne Bolton
Title: Vice President, Compliance &
Chief Compliance Officer


AIM Private Asset Management, Inc.


By: /s/ Todd L. Spillane
------------------------------------
Name: Todd L. Spillane
Title: Chief Compliance Officer


AMVESCAP National Trust Company


By: /s/ Kevin Lyman
------------------------------------
Name: Kevin Lyman
Title: General Counsel


Atlantic Trust Company, N.A.


By: /s/ Kathleen Oldenborg
------------------------------------
Name: Kathleen Oldenborg
Title: Ghief Compliance Officer


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/ Patrick Riviere
------------------------------------
Name: Patrick Riviere
Title: Managing Director


INVESCO Asset Management Osterreich GmbH


By: /s/ Thomas Kraus
------------------------------------
Name: Thomas Kraus
Title: Managing Director


INVESCO Global Asset Management (N.A.),
Inc.


By: /s/ Jeffrey Kupor
------------------------------------
Name: Jeffrey Kupor
Title: General Counsel


INVESCO GT Management Company S.A.


By: /s/ Nick Styman
------------------------------------
Name: Nick Styman
Title: Director of European Compliance


INVESCO Institutional (N.A.), Inc.


By: /s/ Jeffrey Kupor
------------------------------------
Name: Jeffrey Kupor
Title: General Counsel


INVESCO Management S.A.


By: /s/ Alain Gerbaldi
------------------------------------
Name: Alain Gerbaldi
Title: Head of Investment Operations


INVESCO Maximum Income Management S.A.


By: /s/ Alain Gerbaldi
------------------------------------
Name: Alain Gerbaldi
Title: Head of Investment Operations


INVESCO Private Capital, Inc.


By: /s/ Jeffrey Kupor
------------------------------------
Name: Jeffrey Kupor
Title: General Counsel


INVESCO Senior Secured Management, Inc.


By: /s/ Jeffrey Kupor
------------------------------------
Name: Jeffrey Kupor
Title: General Counsel


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/ Alain Gerbaldi
------------------------------------
Name: Alain Gerbaldi
Title: Head of Investment Operations


INVESCO Kapitalanlagegesellschaft GmbH


By: /s/ Stephanie Ehrenfried
------------------------------------
Name: Stephanie Ehrenfried
Title: Head of Legal CE


PowerShares Capital Management LLC


By: /s/ Kevin Gustafson
------------------------------------
Name: Kevin Gustafson
Title: General Counsel & COO


Stein Roe Investment Counsel, Inc.


By: /s/ Greg Campbell
------------------------------------
Name: Greg Campbell
Title: General Counsel