Apply Sample Rate to a Total depending on date

Hello. i have a daily total table which I need to apply a sample rate depending on the date. 

I have created a table to show how I would like to split the total e.g. 0.75, will show the result for 75 per cent of the total.

however, the sample rate changes over time and I would like to record that.

i am happy to change the structure of the table or anything that's needed. i have a date table set up also.

Thanks in advance!