1999-2007

1999-2008

2009-2013

1999-2013

Coeff.

t

Coeff.

t

Coeff.

t

Coeff.

t

k

−0.133

−3.426

−0.100

−2.542

0.263

12.265

0.146

7.896

0.351

29.741

0.341

29.425

0.138

4.836

0.271

41.114

0.111

4.620

0.096

5.300

0.145

5.316

0.131

7.903

−0.242

−6.388

−0.250

−7.132

−0.235

−6.707

−0.144

−5.721

long

0.893

0.880

0.287

0.905

short

0.437

0.480

0.822

0.444