the following tables present a reconciliation of the beginning and ending balances of the fair value measurements using significant unobservable inputs ( level 3 ) for 2017 and 2016 , respectively: .
in 2017 what was the percent of the return on assets to the balance at the end of december
purchases , issuances and settlements , net . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ( 4 ) balance as of december 31 , 2016 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $ 140 the company 2019s postretirement benefit plans have different levels of funded status and the assets are held under various trusts . the investments and risk mitigation strategies for the plans are tailored specifically for each trust . in setting new strategic asset mixes , consideration is given to the likelihood that the selected asset allocation will effectively fund the projected plan liabilities and meet the risk tolerance criteria of the company . the company periodically updates the long-term , strategic asset allocations for these plans through asset liability studies and uses various analytics to determine the optimal asset allocation . considerations include plan liability characteristics , liquidity needs , funding requirements , expected rates of return and the distribution of returns . strategies to address the goal of ensuring sufficient assets to pay benefits include target allocations to a broad array of asset classes and , within asset classes , strategies are employed to provide adequate returns , diversification and liquidity . in 2012 , the company implemented a de-risking strategy for the american water pension plan after conducting an asset-liability study to reduce the volatility of the funded status of the plan . as part of the de-risking strategy , the company revised the asset allocations to increase the matching characteristics of fixed-income assets relative to liabilities . the fixed income portion of the portfolio was designed to match the bond-like and long-dated nature of the postretirement liabilities . in 2017 , the company further increased its exposure to liability-driven investing and increased its fixed-income allocation to 50% ( 50 % ) , up from 40% ( 40 % ) , in an effort to further decrease the funded status volatility of the plan and hedge the portfolio from movements in interest rates . in 2012 , the company also implemented a de-risking strategy for the medical bargaining trust within the plan to minimize volatility . in 2017 , the company conducted a new asset-liability study that indicated medical trend inflation that outpaced the consumer price index by more than 2% ( 2 % ) for the last 20 years . given continuously rising medical costs , the company decided to increase the equity exposure of the portfolio to 30% ( 30 % ) , up from 20% ( 20 % ) , while reducing the fixed-income portion of the portfolio from 80% ( 80 % ) to 70% ( 70 % ) . the company also conducted an asset-liability study for the post-retirement non-bargaining medical plan . its allocation was adjusted to make it more conservative , reducing the equity allocation from 70% ( 70 % ) to 60% ( 60 % ) and increasing the fixed- income allocation from 30% ( 30 % ) to 40% ( 40 % ) . the post-retirement medical non-bargaining plan 2019s equity allocation was reduced due to the cap on benefits for some non-union participants and resultant reduction in the plan 2019s liabilities . these changes will take place in 2018 . the company engages third party investment managers for all invested assets . managers are not permitted to invest outside of the asset class ( e.g . fixed income , equity , alternatives ) or strategy for which they have been appointed . investment management agreements and recurring performance and attribution analysis are used as tools to ensure investment managers invest solely within the investment strategy they have been provided . futures and options may be used to adjust portfolio duration to align with a plan 2019s targeted investment policy. .