My VCI went from 98-108 to 131-142 in just 14 months. I am an autodidact, but is such increase common?

Just a year ago I scored in the 57th percentile, now I am at 99.4 (VCI). Both working memory and processing speed saw an increase of 10 points as well. Only perceptual reasoning saw a decrease of 7 points. Ultimately, my FSIQ increased with a total of 10 points in just 14 months, and in a lifetime with 33 points. How come?