Decade	Start level	End level	Avg level	Rate of increase	Avg level - 280	Ratio F/E
1958-1968	315.34	323.04	319.190	0.770	39.190	50.90
1968-1978	323.04	335.40	329.220	1.236	49.220	39.82
1978-1988	335.40	351.57	343.485	1.617	63.485	39.26
1988-1998	351.57	366.70	359.135	1.513	79.135	52.30
1998-2008	366.70	385.60	376.150	1.890	96.150	50.87
2008-2018	385.60	408.40	397.000	2.280	117.000	51.32
			Averages:	1.551	74.030	47.73