Grey Clustering Evaluation for the Cooperation Efficiency of PPP Project: Taking Beijing Metro Line 4 as an Example

Table 3

Percentage distribution of the respondents’ profile.

Index	Range	Public sector	Private sector	Public
Age	18-30	2	11	9
	31-50	14	30	16
	50+	5	7	7
Education level	High school graduation	-	-	9
	Post high school	21	48	23
Years of PPP project experience	<3 years	2	7	-
	3~5 years	5	23	-
	6~10 years	11	14	-
	>10 years	2	5	-