Are students becoming illiterate?

I’m in my second year of community college after taking an 8 year break after high school. This week for the first time I had to do a group project with other students. I was shocked that more than half the students in my class were practically illiterate. They are all 18/19 and right out of high school. Some of them struggled to write single sentences that made sense even when typing with spell check. I had to do almost all the work myself. Has our education system gotten that bad since I left high school? How in the hell are these kids graduating and passing standardized tests?