Table 1 The results of ADF test

gN	t-Stat.	Prob.	VolN	t-Stat.	Prob.
gN_Total	-4.4540	0.0004	VolN_Total	-4.4155	0.0004
gN_SMetro	-6.7637	0.0000	VolN_SMetro	-6.1524	0.0000
gN_5Cities	-4.5882	0.0002	VolN_5Cities	-3.1563	0.0248
gN_NMetro	-4.8718	0.0001	VolN_NMetro	-2.9208	0.0455

We reported the results estimated by using the formular which has only intercept in test equation.
Null hypothesis: gN has a unit root or VolN has a unit root.