| Countries | Less than 1.4 mg O₂/l (%) | 1.4-2.0 mg O₂/l (%) | 2.0-3.0 mg O₂/l (%) | 3.0-4.0 mg O₂/l (%) | Greater than 4.0 mg O₂/l (%) |
|---|---|---|---|---|---|
| Albania (26) | 0.0 | 0.0 | 0.0 | 0.0 | 100.0 |
| Austria (81) | 33.3 | 50.6 | 16.0 | 0.0 | 0.0 |
| Belgium (92) | 45.7 | 17.4 | 19.6 | 6.5 | 10.9 |
| Bulgaria (103) | 25.2 | 18.4 | 30.1 | 17.5 | 8.7 |
| Croatia (48) | 64.6 | 10.4 | 10.4 | 6.3 | 8.3 |
| Cyprus (27) | 74.1 | 11.1 | 11.1 | 0.0 | 3.7 |
| Czechia (868) | 9.6 | 25.3 | 32.4 | 15.8 | 16.9 |
| Estonia (100) | 45.0 | 43.0 | 12.0 | 0.0 | 0.0 |
| Finland (10) | 30.0 | 20.0 | 50.0 | 0.0 | 0.0 |
| Germany (163) | 33.1 | 22.7 | 30.1 | 9.2 | 4.9 |
| Ireland (182) | 91.2 | 7.7 | 0.5 | 0.5 | 0.0 |
| Italy (2,445) | 29.2 | 12.3 | 30.0 | 12.5 | 16.0 |
| Kosovo* (47) | 14.9 | 2.1 | 6.4 | 6.4 | 70.2 |
| Latvia (34) | 67.6 | 23.5 | 8.8 | 0.0 | 0.0 |
| Lithuania (442) | 14.9 | 36.7 | 37.1 | 7.9 | 3.4 |
| North Macedonia (18) | 0.0 | 5.6 | 44.4 | 16.7 | 33.3 |
| Poland (3,268) | 7.4 | 22.8 | 32.8 | 20.1 | 16.9 |
| Portugal (124) | 16.1 | 1.6 | 28.2 | 46.0 | 8.1 |
| Romania (121) | 0.0 | 32.2 | 26.4 | 20.7 | 20.7 |
| Serbia (35) | 8.6 | 34.3 | 45.7 | 11.4 | 0.0 |
| Slovakia (16) | 18.8 | 12.5 | 62.5 | 6.3 | 0.0 |
| Slovenia (20) | 100.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Spain (2,504) | 1.0 | 5.8 | 43.6 | 14.0 | 35.6 |