import numpy as np
import matplotlib.pyplot as plt
x = [1,2,3,5,6,7,8,9,10,12,13,14,15,16,18,19,21,22]
y = [100,90,80,60,60,55,60,65,70,70,75,76,78,79,90,99,99,100]
#a method that lets us make a polynomial model:
model = np.poly1d(np.polyfit(x,y,3))
#Then specify how the line will display, we start
#at position 1, and end at position 22
line = np.linspace(1, 22, 100)
plt.scatter(x, y)
plt.plot(line, model(line))
plt.show()