Help with calculating portfolio returns over rolling 30 yr periods

Hi All

Attached is workbook in which annual data for stocks, bonds and inflation. I'd like to calculate rolling 30 yr portfolio returns from 1928 thru 2019. The portfolio starts at 90% stocks and 10% bonds The bond portion starts increasing as shown starting in the 17th year. The portfolio starts with $1000 and an inflation adjusted $1000 is added each year. I've calculated the results for the first 30 year period. I don't know how to combine the rolling periods with the annual bond adjustments. Any help is greatly appreciated!

Charlie