Seriously, who’s measuring, and does it matter? What’s to say what’s “native Semitic”? Does that mean original Akkadian (the antecedent to Hebrew), or Northwestern Semitic/Canaanite which it became (and which itself had many foreign influences, from the Hittites and Sea Peoples as well as Egyptian)?
Do words such as Sanhedrin (from the Greek for “Council”), avir (air), cartis (card), téatron (theatre), itztadion (stadium)—all from Greek at least a thousand years before any modern European language began to emerge—count as “native”?.
And what about the many hundreds of words of Aramaic origin (like davqa, adraba, abba, eshtaqad, etc.) which didn’t exist in Old Testament times, but were introduced by the Jews returning from Babylon in the Second Temple period?
Many of the words that Eliezer Ben-Yehudah introduced in the late 1800s/early 1900s to bolster the biblical/Talmudic vocabulary to suit the modern world were taken from Arabic, so they are Semitic but artificially introduced, and many others (such as mivreshet, glidah, bubah) he derived from Western European languages.
Then of course there are all the more recently Hebraized European words such as informatziah, qonteqst, alternativah, which co-exist alongside native equivalents such as meida, heqsher and ḥalufah (much as English has Anglo-Saxon equivalents for many words of French/Latin origin).
For as long as it has existed, Hebrew has been a composite language (much like the people itself), and it will continue to be. Today it is absorbing many Arabic words through the colloquial language—those, too, are Semitic, but not part of the Hebrew of ancient times. So don’t try to measure percentages, and just love it for the mongrel that it is.