Year	Number
1974	22.7009
1976	20.80111
1984	19.09895
1985	20.17427
2003	16.47742
2005	18.03704
2007	22.34916
2008	20.8934
2009	21.90081
2010	21.4222
2011	20.86307
2012	20.29138