Year	Number
1990	13.26976
1991	12.66429
1992	12.30966
1993	11.66478
1994	11.52308
1995	12.53899
1996	13.05469
1997	15.56879
1999	12.59458
2000	13.24936
2001	13.53472
2002	13.2212
2003	13.24313
2004	12.97961
2005	12.75773
2006	12.39943
2007	12.10284
2008	11.49866
2009	11.25259
2010	10.4993
2011	9.89848
2012	9.57243
2013	9.58607
2014	9.376
2015	9.34236
2016	9.22639
2017	9.91073
2018	9.86318