Class

1

2

3

4

5

(0, 40)

[40, 80)

[80, 160)

[160, 320)

[320, +∞)

(0, 75);

[75, 150)

[150, 225);

[225, 300)

[300, 450);

[450, 600)

[600, +∞)

Level

Nile to very low; low

Lower-moderate;

higher-moderate

High; very high

Extremely high

Ultra high