Year	Number
2000	2.4687915007
2001	2.4807436919
2002	2.4933598938
2003	2.5059760956
2004	2.5166002656
2005	2.5146082337
2006	2.5258964143
2007	2.5869853918
2008	2.6022576361
2009	2.8545816733
2010	2.8911022576
2011	2.812749004
2012	2.906374502
2013	2.8937583001
2014	2.7383798141
2015	2.7788844622
2016	2.786188579
2017	2.6620185923
2018	2.0717131474
2019	2.0285524568
2020	2.0005312085