Year	Number
2000	2.109171213697455
2001	2.027114204186519
2002	2.4241614499021344
2003	2.4284681544278994
2004	2.1741648206919573
2005	2.4118180146332184
2006	3.8018946620686553
2007	3.8480061861169412
2008	2.2732234413794736
2009	4.456276060895878
2010	3.939357117318295
2011	3.354666847777662
2012	3.362993902737478
2013	3.0382465715507387
2014	2.7809042139471383
2015	2.958436127816132
2016	3.5967810741089354
2017	3.684124565026197
2018	2.9342092652280334
2019	3.0748237549042545
2020	2.8598266802566608
2021	2.5309151949258433
2022	2.0222346014511703
2023	2.2151370895244074