Calculation of the denominator for the number of lines inserted annually
| Units by number of lines sited per year | Mean number of lines sited per year | Number of units within this banding | Estimated total number of lines sited per year |
|---|---|---|---|
| <20 | 10 | 51 | 510 (6%) |
| 20–50 | 35 | 58 | 2030 (21%) |
| 50–100 | 75 | 33 | 2475 (27%) |
| 100–200 | 150 | 21 | 3150 (34%) |
| >200 | 200 | 5 | 1000 (11%) |
| Total | 168 | 9165 |