| Progress | Difficulty | Peak |
|---|---|---|
| Vol 1-3 | 2.78/5 | 4.46/5 |
| Vol 4-6 | 3.02/5 | 4.64/5 |
| Vol 7-9 | 3.13/5 | 4.58/5 |
| Vol 10-12 | 3.17/5 | 4.65/5 |
| Vol 13-15 | 3.55/5 | 4.69/5 |
| Vol 16-18 | 3.85/5 | 4.70/5 |
| Vol 19-21 | 3.39/5 | 4.73/5 |
| Vol 22-24 | 3.66/5 | 4.70/5 |
| Vol 25-27 | 3.02/5 | 4.58/5 |
| Vol 28-30 | 3.44/5 | 4.69/5 |
| Vol 31-33 | 2.84/5 | 4.66/5 |
| Vol 34-36 | 3.01/5 | 4.54/5 |
| Vol 37-39 | 3.30/5 | 4.64/5 |
| Vol 40-42 | 3.23/5 | 4.65/5 |
| Vol 43-45 | 3.09/5 | 4.62/5 |
| Vol 46-48 | 3.10/5 | 4.58/5 |
| Vol 49-51 | 3.21/5 | 4.62/5 |
| Vol 52-54 | 3.28/5 | 4.67/5 |
| Vol 55-57 | 3.34/5 | 4.60/5 |
| Vol 58-60 | 3.65/5 | 4.69/5 |
| Vol 61-63 | 3.17/5 | 4.56/5 |
| Vol 64-66 | 3.45/5 | 4.68/5 |
| Vol 67-69 | 3.65/5 | 4.67/5 |
| Vol 70-72 | 3.26/5 | 4.68/5 |
| Overall | 3.28/5 | 4.73/5 |