Year	Number
1983	21.17847
1984	23.00682
2001	21.88952
2002	20.33956
2003	20.3388
2004	21.1101
2010	24.89103
2011	24.85464
2012	23.43248
2013	23.11052
2014	22.68402
2015	22.04845
2016	20.75702
2017	20.36342
2019	18.60802