Number of unique characters in the X most common words? I assume this would be wouldn't be too hard to calculate with a proper database, but does anyone know the number of unique characters/morphemes used in the 5000, 10000, 30000, etc. most common words? 

For example, I heard that 6000 characters covers over 99% of words in modern usage, and assuming that a native's passive vocabulary is around 30000, I conclude that there are approximately 6000 unique characters used in the 30000 most common words (this could be way off).

I am curious about these statistics. Preferably, someone has a nice plot showing the relationship between the two, but a few data points would also be appreciated.
I write a simple script to compute the plot from an old phrase frequency data.



If you're interested, here is the raw data.

These data are for Taiwan's traditional Chinese,
but the statistics should be very similar to simplified Chinese.