Formatting percentages [closed]

According to the SI rules for percentages (http://www.bipm.org/en/publications/si-brochure/) the value should always be separated from the % sign by a space; however, when writing text it always seems a little odd to include the space and I very rarely see it written that way.

My salary increased by 56 % last week. My salary increased by 56% last week.

Is there a different rule for written English?

Chicago Manual of Style, section 9.23 15th edition (p. 385) "Note also that no space appears between the numeral and the symbol %." So, I suppose it depends on the forum. If it is a scientific journal and they mandate SI rules, then use a space; if it is a book for a non-specialized audience then delete the space.