You may be interested in this discussion and there are others on the similar topic.
If you want one minute data you must restrict your time period of data to a maximum of 24 hours per API call.
I think if I had time I could create a python program that calls the API to get each day of data and output it into a spreadsheet. The idea has been on my list of ideas to do but I am busy with other projects atm.
But you can do it manually as you are and you will probably figure out how to make your process semi automatic.
cheers Ian 