Absolutely it's a very good and safe investment, and yes looking at annual return as a percentage of your portfolio in this case is definitely irrelevant since your return isn't based on the size of your portfolio. The point of my reply was to show why dobby41 and you disagreed about the return, since you guys were looking at different ways of calculating return.
Anyway I made a spreadsheet
https://docs.google.com/spreadsheets...it?usp=sharing
edit: Just realised the kiwisaver govt contribution is $521.43 and not $512, but the %'s remain the same regardless