Year	Number
2002	6.0797836376
2003	6.1347757494
2004	6.1897678612
2005	6.244759973
2006	6.2846517918
2007	6.3245436105
2008	7.0317782285
2009	6.3739012847
2010	6.2576064909
2011	5.7491548343
2012	6.2745098039
2013	7.8133874239
2014	6.6281271129
2015	6.0649087221
2016	5.9993238675
2017	6.2974983097
2018	6.4976335362
2019	6.3826910074
2020	6.7816091954