It could be worse. I could be writing at a postgraduate level. Many years ago when I worked as an accounting manager in a biotech firm I ran a similar test on two samples of my writing. My sermons consistently came out at sixth-grade level and my work correspondence at grade 17 (post-grad). I took pride in both ratings, with my sermons accessible and my work very carefully nuanced and technical. One had to get past the legal department and the other past a bright child. You know where my heart was.
h/t to Wyld's Q&A for the quiz and to FranIAm for pointing me to Wyld.
UPDATE: Oh dear, what have I stirred up? See comment's at Mimi's shelter for reprobates.