The way you calaculated it could be repeated for 2 seats per plane and get very close to a one percent change in load factor.
one percent of 189 seats is 1.89 seats. We have no idea if the 88% and 89% are 87.6% and 89.4% or 88.4% and 88.6%. Ryanair keep reducing the detail of data suppled. in 2007 they told us the exact number of seats sold.
I guess someone know exactlly the number of sectors and can work out an exact load factor.