Every area was devided into 5 levels (0 - 6): 0: 0%; 1: 1 - 9%; 2: 10 - 29%; 3: 30 - 49%; 4: 50 - 69%; 5: 70 - 89%; 6: 90-100%.
Mỗi vùng được chia 7 mức độ (0-6): 0: 0%; 1: 1-9%; 2: 10-29%; 3: 30-49%; 4: 50-69%; 5: 70-89%; 6: 90-100%.