Year	Number
1971	13.25381
1972	14.63023
1973	14.34555
1974	13.85838
1975	14.55947
1976	14.11882
1977	12.75372
1978	11.53731
1999	26.25981
2000	23.35051
2001	23.63499
2002	23.86987
2003	23.87041