for 2017 , the investment strategy for pension plan assets is to maintain a broadly diversified portfolio designed to achieve our target of an average long-term rate of return of 5.56% ( 5.56 % ) . while we believe we can achieve a long- term average return of 5.56% ( 5.56 % ) , we cannot be certain that the portfolio will perform to our expectations . assets are strategically allocated among debt and equity portfolios to achieve a diversification level that reduces fluctuations in investment returns