Verified answer

I would write it as,

"We have to wonder WHY Internet Explorer still manages to HAVE THE LARGEST USER BASE, holding well over forty-percent share in the Web-browser market. It has been outstripping all the other contenders despite it being disliked by A LARGE NUMBER OF people for its CLUNKY, SLOW browsing speed.

With respect to Chrome, it is tied with Firefox for second place on approxIMATELY twenty-five-percent share overall. It's market share has soared significantly over the course of the last two years; from less than A measly 5% to the current 25%. It remains to be seen whether the astounding acceleratED growth of Chrome may completely change the market share landscape in a few years’ time."

My changes are in caps.

sentence a) is greater suited for written English, while sentence b) may be greater suited in spoken English. So as an occasion, in case you have been in an examination or writing a letter, you will possibly use sentence a). in spite of the undeniable fact that, in case you have been having a communication with a pal, you may use sentence b). They the two recommend surprisingly plenty a similar ingredient, yet a) is greater marvelous than b) :)

why (instead of how come)

approximately (not approx)

omit mere

use word other than measly...too oily sounding...

omit astoundingly

You need to have all letters or all numbers for your percents. no mixing.

You have too many flowery adjectives...like measly (paltry is better)

your english is better than most people who have been speaking it all of thier lives. :) I see nothing wrong here.