Paul Graham, FRM® is analyzing the sales growth of a baby product launched three years ago by a regional company. He assesses that three factors contribute heavily towards the growth and comes up with the following results:

$Y = b + 1.5X_1 + 1.2X_2 + 3X_3$

Sum of Squared Regression [SSR] = 869.76
Sum of Squared Errors [SSE] = 22.12

Determine what proportion of sales growth is explained by the regression results._