Year,1975,1976,1977,1978,1979,1980,1981,1982,1983,1984,1985,1986,1987
Lean,2.9642,2.9644,2.9656,2.9667,2.9673,2.9688,2.9696,2.9698,2.9713,2.9717,2.9725,2.9742,2.9757