Table 4.

Unit root test results.

Variables	ADF		PP		Zivot-Andrew
	Level	1st difference	Level	1st difference	Level	1st difference	Break
LCO2	−4.478	−9.287**	−4.547	−7.754	−2.153	−7.574*	1997
LGDPC	−2.873	−3.187*	−2.565	−5.876**	−4.658	−11.769*	2000
LTD	−1.397	−3.539**	−3.870	−5.397*	−3.793	−8.375*	2002
LSG	−2.439*	−4.287	−2.434*	−5.328	−3.843*	−5.054	2012
LENE	−1.948	−2.176*	−2.154	−5.932*	−3.145	−8.478**	2016
LSI	−1.328	−3.870*	−1.658	−5.357*	−1.356	−9.542*	2018