Schedule
| Tax Year | Percentage |
|---|---|
| 1978–79 | 522.3 |
| 1979–80 | 449.2 |
| 1980–81 | 358.8 |
| 1981–82 | 284.3 |
| 1982–83 | 249.0 |
| 1983–84 | 224.1 |
| 1984–85 | 200.1 |
| 1985–86 | 181.5 |
| 1986–87 | 158.5 |
| 1987–88 | 140.7 |
| 1988–89 | 121.4 |
| 1989–90 | 99.8 |
| 1990–91 | 86.2 |
| 1991–92 | 69.2 |
| 1992–93 | 58.8 |
| 1993–94 | 51.3 |
| 1994–95 | 46.7 |
| 1995–96 | 40.5 |
| 1996–97 | 36.7 |
| 1997–98 | 30.2 |
| 1998–99 | 24.5 |
| 1999–2000 | 19.5 |
| 2000–2001 | 12.4 |
| 2001–2002 | 8.1 |
| 2002–2003 | 3.6 |