| 1991 | 1992 | 1993 | 1994 | 1995 | 1996 | 1997 | 1998 | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | |
| Disminuye | 18.9 | 21.5 | 23.7 | 12.1 | 9.6 | 11.8 | 8.9 | 10.5 | 13.0 | 11.9 | 11.3 | 12.7 | 13.1 | 10.3 | 12.8 | 11.2 | 12.7 | 20.5 | 27.8 | 23.6 | 22.5 | 49.6 | 17.2 | 15.5 | 9.4 | 9.9 | 12.5 | 7.4 | 9.9 | 12.3 | 9.0 | 8.2 | 5.0 |
| Constante | 46.2 | 52.5 | 49.9 | 51.1 | 55.4 | 54.7 | 51.2 | 54.4 | 58.8 | 57.9 | 60.9 | 60.1 | 65.4 | 66.9 | 65.1 | 61.7 | 63.9 | 59.0 | 59.1 | 62.4 | 61.8 | 36.8 | 63.2 | 67.0 | 67.8 | 66.0 | 69.7 | 72.2 | 69.4 | 58.9 | 66.0 | 65.0 | 63.3 |
| Aumenta | 34.9 | 26.0 | 26.4 | 36.8 | 35.0 | 33.5 | 39.9 | 35.1 | 28.2 | 30.2 | 27.8 | 27.2 | 21.5 | 22.8 | 22.1 | 27.0 | 23.4 | 20.5 | 13.8 | 14.0 | 15.7 | 13.6 | 19.5 | 17.5 | 22.8 | 24.1 | 17.8 | 20.4 | 20.7 | 28.8 | 25.0 | 26.8 | 31.7 |