Year	Number
1971	4712
1972	5106
1973	5373
1974	5614
1975	5791
1976	6178
1977	6834
1978	6994
1979	7484
1980	8314
1981	9081
1982	10029
1983	11366
1984	13390
1985	14453
1986	15551
1999	47358
2000	53510
2001	56893
2002	58127
2003	72977
2004	82014
2005	95557
2006	99454
2007	102090
2008	104842
2009	111019
2010	112435
2011	115198
2012	121275
2013	129866
2014	136504
2015	141401
2016	146839
2017	154667
2018	163065