Year	Number
1996	17.5
1998	14.4278602600098
2000	13.4328355789185
2002	10.4477615356445
2003	13.4328355789185
2004	13.4615383148193
2005	12.9807691574097
2006	14.9038457870483
2007	17.3076915740967
2008	19.7115383148193
2009	20.3791465759277
2010	20.3791465759277
2011	23.0046939849854
2012	18.7793426513672
2013	23.474178314209
2014	26.1083736419678
2015	27.5862064361572
2016	31.5270938873291
2017	29.0640392303467
2018	26.2135925292969
2019	27.0531406402588
2020	27.5362319946289
2021	26.0869560241699
2022	27.5362319946289