Year	Number
1987	11.4532482163
1988	13.3214419827
1989	15.1896357492
1990	17.0578295156
1991	18.926023282
1992	20.7942170484
1993	22.6624108149
1994	24.5306045813
1995	26.3987983477
1996	28.2669921142
1997	30.1351858806
1998	32.003379647
1999	33.8715734134
2000	35.7397671799
2001	37.6079609463
2002	39.4761547127
2003	38.2838903492
2004	37.0916259857
2005	35.8993616222
2006	34.7070972587
2007	33.5148328952
2008	33.3094723995
2009	33.1041119039
2010	32.9012157341
2011	32.6966766804
2012	32.4880304168
2013	32.2826699211
2014	32.0773094255
2015	31.8719489298
2016	31.9376642884
2017	31.3462260608
2018	35.405385383
2019	35.405385383
2020	35.405385383