Year	Number
1998	38.60889
1999	32.1968
2000	32.49791
2001	33.9017
2005	31.52842
2006	29.98923
2008	31.06741
2009	25.68674
2010	24.68146
2011	22.04424
2012	22.58019
2013	16.20572
2014	16.57639
2015	13.29651
2016	13.47821
2017	12.89655
2018	12.63093