The pleco dictionary shows frequencies from 1 to 5. How many words are in each category? How have the frequencies been measured? I am familiar with some research about the frequencies years ago. I especially would like to know if the frequencies are based on research about written or spoken language. Additionally, I want to ask to add frequencies for spoken language, not just for written language. And frequencies for words, not just for characters would also be helpfull. Can anyone help me with these questions please?