Year % 1990 0 1991 0 1992 0 1993 0 1994 0 1995 0 1996 10 1997 7.14285714285714 1998 5 1999 6.89655172413793 2000 7.14285714285714 2001 6.45161290322581 2002 8.98876404494382 2003 8.87096774193548 2004 9.88372093023256 2005 11.0091743119266 2006 12.5984251968504 2007 13.4275618374558 2008 14.4230769230769 2009 15.2492668621701 2010 15.5913978494624 2011 16.5841584158416 2012 17.2811059907834 2013 17.8879310344828 2014 18.2926829268293 2015 18.4466019417476 2016 19.3245778611632 2017 19.7106690777577 2018 20 2019 20.1030927835052 2020 20 2021 20.259319286872 2022 20.414673046252