The phrase "several percent" is correct and usable in written English.
You can use it when talking about a measure of something in terms of a percentage. For example: "The stock market saw an increase of several percent last week."
Certain magmas, such as those which form granites, contain several percent water dissolved in them.
These zirconium minerals generally have a hafnium content that varies from a few tenths of 1 percent to several percent.
Long gone are the Marshall Plan times, when we dedicated several percent of our gross domestic product to European reconstruction.
The added business has probably increased their revenues by several percent -- nothing to scoff at, Mr. Connor said.
The contents of alumina, ferric oxide, and alkalis are variable but may amount to several percent in light-coloured opals and more if pigmenting minerals are also present.
The emerging economies facing the biggest challenges in recent months have been wrestling with broadly measured trade deficits equal to several percent or more of their annual output.
Almost all sedimentary rocks are iron-bearing in the sense that mudrocks, sandstones, and carbonates typically have an iron content of several percent.
V.I.E.'s account for differing proportions of these companies' income and assets, ranging from several percent to as much as 100 percent.
I have no idea how that last statistic compares with the wiper of the old car, but I'm sure it's at least several percent better.
Such downpours have been estimated in some such countries to blunt economic growth by several percent, according to World Bank experts on disasters.
The pay cuts, will be "several percent" from each paycheck and will start at the section chief level and go up, a spokeswoman for Fujitsu, Yuri Momomoto, said.
