its 2k uni teachers for a uni, "plenty" of workers might be a perspective...
if you corp salaries are much higher than you gov sals, then many of your teachers will leave the education field for more "fruitful," professions
some times if you buy allot of pop, you will get a "pop bubble," that will result in allot of workers retiring at one time.
what else, i'm sure their are more reasons for this to happen, but most likely, you transposed a number and typed in 500 instead of 200 for schools...
i'd also like to leave you with... your individual education indexes should be roughly the same, if you have 120 index for hs, and 180 for schools, and unis, then you overall index will probably be about 119... it doesn't average out