Table 1 The 30 regions studied in the current study
Provinces and cities | Category I | Category II | Category III |
|---|---|---|---|
Beijing (BJ) | Dongcheng (DF) | Changping (CP) | Fangshan (FS) |
Guangdong (GF) | Guangzhou (GZ) | Shantou (ST) | Shaoguan (SG) |
Zhejiang (ZJ) | Hangzhou (HZ) | Ningbo (NB) | Quzhou (QZ) |
Hubei (HB) | Wuhan (WH) | Jinzhou (JZ) | Enshi (ES) |
Shandong (SD) | Jinan (JN) | Qingdao (QD) | Jinin (JN) |
Jilin (JL) | Changchun (CC) | Jilin (JL) | Yanbian (YB) |
Chongqing (CQ) | Yubei (YB) | Yongchuan (YC) | Fengdu (FD) |
Yunnan (YN) | Kunming (KM) | Pu’er (PE) | Diqing (DQ) |
Inner Mongolia (IM) | Hohhot (HHHT) | Hulunbeier (HLBE) | Bayannaoer (BYNE) |
Gansu (GS) | Lanzhou (LZ) | Tianshui (TS) | Wuwei (WW) |