What does 数% mean in 数%程度でしかなく?

The phrase in question comes from the Japanese global warming article.

その一方で太陽放射等の自然要因による変化の寄与量は人為的な要因の数%程度でしかなく、自然要因だけでは現在の気温の上昇は説明できないことが指摘されている

I think I understand the gist of 数%程度でしかなく. My reading is, '[accounts for] just a few percent [of the change]'. However, I've never encountered 数 used as a prefix like this before to represent a small change. Can someone clarify the meaning of this phrase? Thanks.

• 数パーセント is less than 10 %. A few, several, small percent and so on. More than or equal to 10%, it is 数10パーセント。 – user25382 Oct 25 '17 at 10:18
• @kimiTanaka, if you say 数10パーセント, wouldn't it mean "a few tens of percent", meaning at least 20 %, since otherwise it's not in plural? If it's close to 10, wouldn't it be more natural to simply say 10パーセント程度? – a20 Oct 25 '17 at 10:40
• @bjorn Ah, sorry. The expression "less than 10 %" is not good. I should have written 数パーセント is around 5%. So, it probably is a few or several percents. Yes, if it's close to 10%, I think10%程度 is more appropriate. According to ejje.weblio.jp/content/%E6%95%B0%E5%8D%81%E5%88%86 数十パーセント　is 10~30%. Thanks for correcting. – user25382 Oct 25 '17 at 11:01