Turns out the problems I was having had nothing to do with decimals but
rather the size of the array I was creating. It appears that I can't
enter a string into the ActiveChart.SeriesCollection(2).Values when the
length of that string is greater than 255 characters. I had no problem
when I had a dozen or so data points but when I had 52 (one for each
week in a year) I started to bump into problems. Through trial and
error I determined it was the length of the string being created in my
code that was causing the problem.

I really wanted to avoid using a dummy column of data for this but it
looks like that's what I'll need to do.

- John