Year	Number
1999	18.26027
2000	18.39565
2001	19.04433
2002	19.78124
2003	20.95044
2004	21.7709
2005	22.69138
2006	23.94724
2007	25.35946
2008	26.76587
2009	27.23731
2010	26.23661
2011	26.93081