Why does the Standard Numeric Format for percentages include a space?

Question

The Back Story

I have some decimal values which I am displaying as strings on a web page as part of a larger string. I started off using a Standard Numeric Format String to output this. E.g.

myDecimal.ToString("P0")

The 0 after the P tells it I want no decimal places. This works as far as it goes, in that my ouput ends up looking something like:

Calculated as above based on the phased minimum Company contribution rate of 2 %

The Space Problem

I really want to get rid of that space between the number and the percentage sign as in some cases it ends up splitting across lines. And also, I prefer the % to butt up to the number.

Possible Workarounds

1. html / css solution

I could put a <nobr> tag or a <span style="white-space: nowrap;"> around it. But, that feels awkward, and anyway I prefer the % to butt right up to the number as I think it looks better. It's how we would write it in reports in this neck of the woods, so it's how I want it on the web page.

2. Custom format string

I am going to end up using a Custom Numeric Format String, E.g.

myDecimal.ToString("0%")

The Question

Is it more common to display percentages with a space between the number and the percentage sign? This would surprise me, but it could be.

Is there a way to tell the Standard Numeric Format String I don't want the space?

Is there any disadvantage to using a Custom Numeric Format String over a Standard Numeric Format String?

Ok - I admit it, that was more than one question - Extra Credit if you answer them all.