Zobrazení grafu: týden | měsíc | půl roku | rok | 5 let | 15 let
| Rok | Maximální | Minimální | Průměr |
|---|---|---|---|
| 1991 | 31.500 | 26.850 | 29.484 |
| 1992 | 29.300 | 26.610 | 28.265 |
| 1993 | 30.086 | 28.222 | 29.158 |
| 1994 | 30.328 | 27.231 | 28.780 |
| 1995 | 28.064 | 25.521 | 26.541 |
| 1996 | 27.969 | 26.025 | 27.147 |
| 1997 | 35.266 | 27.095 | 31.708 |
| 1998 | 36.104 | 28.376 | 32.272 |
| 1999 | 36.351 | 29.562 | 34.572 |
| 2000 | 42.127 | 34.879 | 38.603 |
| 2001 | 40.287 | 34.836 | 38.033 |
| 2002 | 37.163 | 29.118 | 32.710 |
| 2003 | 30.348 | 25.654 | 28.207 |
| 2004 | 27.655 | 22.344 | 25.704 |
| 2005 | 25.402 | 21.968 | 23.953 |
| 2006 | 24.588 | 20.761 | 22.588 |
| 2007 | 21.836 | 17.662 | 20.292 |
| 2008 | 20.438 | 14.454 | 17.079 |
| 2009 | 23.333 | 16.886 | 18.986 |
| 2010 | 21.702 | 17.122 | 19.107 |
| 2011 | 20.100 | 16.265 | 17.686 |
| 2012 | 21.133 | 18.448 | 19.576 |
| 2013 | 20.323 | 18.657 | 19.568 |
| 2014 | 22.797 | 19.618 | 20.750 |
| 2015 | 25.963 | 22.834 | 24.577 |
| 2016 | 26.068 | 23.383 | 24.438 |
| 2017 | 26.017 | 21.279 | 23.403 |
| 2018 | 21.399 | 20.163 | 20.658 |