年份

1997

−1031.2324

1998

−973.8633

1999

−912.7124

2000

−841.6464

2001

−762.2933

2002

−667.6361

2003

−556.2900

2004

−412.1504

2005

−260.5218

2006

−75.9737

2007

152.3558

2008

366.3184

2009

602.5483

2010

894.6814

2011

1194.2659

2012

1490.4779

2013

1793.6719