Year	Number
1970	10890
1971	11643
1972	12468
1974	16995
1975	19749
1976	21986
1977	24899
1978	28586
1980	33487
1982	41592
1983	46004
1984	51497
1986	69994
1991	67501
2013	180204
2014	197208
2015	261249
2016	253285
2017	252425