0Your grammar is okay, but your use of "vocabulary" isn't quite right. 3000 words isn't 80% of the (entire) vocabulary -- that would imply that there are only 3750 words in total. However, this core of 3000 words are 80% of the words used in normal conversation.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.