a) Data from 1980 to 1992 are the figures of state-owned and collective-owned construction enterprises. Data from 1993 to 1995 are the figures of all economic types
of construction enterprises above towns. The statistical coverage from 1996 to 2001 included the fourth and higher grades construction enterprises (old classification of grades),
and that since 2002 included all grades construction enterprises, both general constructing contractors and professional contractors (excluding the construction enterprises
of work subcontractors). Therefore the data were not comparable with the data of the previous years. The same as in the following table.
b) The number of employed persons refers to the annual average number from 1993 to 1997.
