Bluebulb Projects' The Measure of Things presents:
70 is about three-fifths the number of Elements on the Periodic Table
In other words, it's 0.5930 times the count of Elements on the Periodic Table, and the count of Elements on the Periodic Table is 1.690 times that amount.
(a.k.a. Periodic Table of the Elements, a.k.a chemical elements) (confirmed elements as of 2016)