| Jahr | Anzahl in Millionen |
|---|---|
| 2004 | 16,80 |
| 2005 | 16,82 |
| 2006 | 16,99 |
| 2007 | 17,17 |
| 2008 | 17,37 |
| 2009 | 18,25 |
| 2010 | 18,38 |
| 2011 | 18,45 |
| 2012 | 19,43 |
| 2013 | 19,76 |
| 2014 | 20,15 |
| 2015 | 20,49 |
| 2016 | 20,83 |
| 2017 | 21,86 |
| 2018 | 22,00 |
| 2019 | 22,13 |
| 2020 | 22,26 |
| 2021 | 22,33 |
| 2022 | 22,48 |
| 2023 | 22,74 |
| 2024 | 22,96 |