A=[66 .5 20 22;
 106.6 1 20 19;
 133.8 1.5 17 15;
 152.3 2 12 13;
 164.7 2.5 11 11;
 173.7 3 9 10;
 180.4 3.5 8 7;
 185.6 4 6 7;
 189.9 4.5 6 8;
 193.4 5 6 6;
 196.1 5.5 5 6;
 198.9 6 3 5;
 201 6.5 3 5;
 202.9 7 4 4;
 203.5 7.5 3 4;
 205.1 8 3 3];

n=3;
p=polyfit([A(:,2);A(:,2)],[A(:,3);A(:,4)],n);
x=linspace(0,8,100)';
y=polyval(p,x);

close all
figure
plot(A(:,2),A(:,3:4),x,y)