To fund her retirement, Helen requires a portfolio with an expected return of 12 per cent per year over the next 30 years. She has decided to invest in Shares 1, 2, and 3, with 25 per cent in Share 1, 50 per cent in Share 2, and 25 per cent in Share 3. If Shares 1 and 2 have expected returns of 9 per cent and 10 per cent per year, respectively, then what is the minimum expected annual return for Share 3 that will enable Helen to achieve her investment requirement?