A 2011 estimate shows 8.7M species on earth with 1.2M species databased. That calculates to 14% named. There are estimates involved in these numbers. In any case we are on pretty safe ground with a statement above that over 70% are yet to be named.

Mora, C., Tittensor, D. P., Adl, S., Simpson, A. G., & Worm, B. (2011). How many species are there on Earth and in the ocean?. PLoS biology, 9(8).