How sensitive is private investment to risk? Plot since 2004 the share of real gross private domestic

Question:

How sensitive is private investment to risk? Plot since 2004 the share of real gross private domestic investment (FRED code: GPDIC1) in real GDP (FRED code: GDPC1) and (on the right scale) a measure of anticipated stock market volatility (FRED code: VIXCSL). Explain the pattern.