I chose newspaper editorials as material. Why? There's less variation among them in terms of difficulty than among novels. There are fewer personal and place names in them than in newspaper articles. They're easy to find.
Here's what I have so far:
For the record, the one English word I didn't know was "exons", encountered in an NYT editorial by Nicholas Kristof. I comfort myself with the near-certainty that he doesn't know what it means either.
What does "Adj. reading speed" mean in my above table? Well, German words, for example, tend to be longer than English ones. So a thousand words in German usually convey more information than a thousand words in English. I decided to quantify this, and then to adjust for it.
When people compare languages, they often use the Lord's Prayer because it's the text that's been translated into the most tongues. However, it's short and sometimes contains archaic vocabulary, which is unrepresentative of modern speech. I decided to go for one of the chief texts of the religion of liberalism instead, the Universal Declaration of Human Rights.
The web site of the High Commissioner of these rights has translations of their Declaration into 501 languages. The document is broken up into chapters. I removed chapter headings ("Chapter 25", for example) before counting the words because I'm more interested in the length of real sentences. In the end I came up with the following numbers:
For Chinese I used the number of characters instead of the number of words. I used the coefficients in the last column to adjust the reading speed numbers above. My entire worksheet can be seen here.
My plan for measuring listening comprehension is to find some audio-books of classic novels and then to calculate the percentage of the words that I understand correctly the first, the second, the third, etc. time that I hear a passage spoken.
The only way to objectively quantify speaking ability is to ask lots of native speakers to grade you. I can't really do that, so those grades will remain subjective in my new system.