Period

Number of Observations

Power Spectrum (β)

Correlation Dimension (D₂)

1961-72

2¹¹

2.044

2.360

1972-83

2¹¹

1.441

2.640

1983-87

2¹⁰

2.118

2.334

1998-02

2¹⁰

2.220

2.280

2003-07

2¹⁰

1.220

2.750

2007-08

2⁹

1.562

2.590

2009-11

2⁹

1.286

2.720