$\alpha$

S.E.

a

S.E.

R²

2012

2.88

0.0337

4.71

0.0172

0.987

2013

2.92

0.0391

4.79

0.0205

0.983

2014

2.67

0.0374

4.63

0.0197

0.981

2015

2.17

0.0405

4.44

0.0237

0.967

2016

2.89

0.0461

4.63

0.0224

0.976

2017

3.13

0.0349

4.60

0.0155

0.988

2018

2.27

0.0293

4.47

0.0168

0.984

2019

2.50

0.0449

4.56

0.0243

0.969

2020

2.48

0.0438

4.65

0.0250

0.970

Pooled data

2.57

0.0176

4.57

0.0093

0.960