Year	Number
1995	21.01338
1996	20.2515
1999	22.03813
2000	21.73399
2001	21.20275
2002	22.07989
2003	20.27768
2004	20.0792
2009	16.03434
2016	16.86987
2017	17.07557
2018	16.77056