| Year | Observation data* | Predicted data* |
| Units in millions | ||
| 1999 | 159.0 | 142.9 |
| 2000 | 161.6 | 167.7 |
| 2001 | 193.6 | 197.5 |
| 2002 | 225.2 | 243.0 |
| 2003 | 273.8 | 275.4 |
| 2004 | 310.7 | 288.3 |
| 2005 | 342.1 | 304.3 |
| 2006 | 342.9 | 327.2 |
| 2007 | 372.7 | 352.5 |