Curve up grades

Sum of monotonic functions = monotonic functions

	D1	D2	D3	D4	D5
ORI	.99	.01	.31	.13	.19
TRANS (sigmoid)	.95	.5	.72	.59	.64

Transform = $\frac{1}{1+\exp(3*{ORI})}$

age = max(physical age*0.8, min((domain age(t-1) + 0.25*response + 0.25*(month_diff(t-1, t))), physical age*1.2)))