Don't forget the power of time! 37 years of accumulation which can be considered long enough to have achieved the expected rate of return of 7.68%. The expected annual saving would be just $5,596!!! ( i.e. only $466 monthly investing).
As compared with a return of 3.68%, you are required to save more!
How much more? $5139 (91%) more on an annual basis.
If these options are not attainable, work towards doing a little bit of both;
saving more money and earning a higher rate of return.
Having a good understanding on these relationship, you probably willing to take the calculated risk, so that you can make better use of that saving on other areas of financial concern.