Year	Number
1994	18.33373
1995	18.55889
1996	19.2149
1997	19.0752
1998	18.42576
1999	19.08485
2000	19.24862
2001	19.46128
2002	19.42004
2003	19.70946
2004	19.63775
2005	19.28743
2006	18.85981
2007	18.70182
2008	18.21934
2009	17.86134
2010	17.75435
2011	17.97626
2012	17.90305
2013	17.47708
2014	17.37467
2015	17.24897
2016	16.72843
2017	16.66975
2018	16.68433