Silicon has three naturally occurring isotopes (Si-28, Si-29, and Si-30). The atomic mass and natural abundance of Si-28 are 27.9769 amu and 92.2 %, respectively. The atomic mass and natural abundance of Si-29 are 28.9765 amu and 4.67 %, respectively. Find the natural abundance of Si-30. Express your answer numerically using two significant figures.