Line chart and margins before and after the plotted data

Hi,

I have done a line chart with the x-axis representing years (data from 1998 to 2011) and the y-axis representing a probability (from 0 to 1).

What I would like to get:
An histogram with in the x-axis only the "real" years (1999, 2000, 2001,...,2011) but keeping a margin between the y-axis and the plotted data (as well as a margin at the end of the plotted data).

My problem:
I can get an histogram with only the "real" years but this way I cannot keep any margin before and after the plotted data, alternatively I can set the axis option with minimum value 1998, the maximum value as 2010.5 and the major unity = 1 (litteral translation - my version is in Spanish). In the latter way I get something more or less similar to my goal (more or less because I can't decide the margin widths) but I am not able to remove the label "2007" from the x-axis.

OK, I have just realized (I apologize for that) that I did this chart as a scatter plot (with lines) because I have two series of data over the same years and I wanted to get them a bit separated in order to keep their bar errors separated (no overlapping). So I did a scatter plot with two data series for y-axis and two data series for the x-axis that were respectively [1998, 1999, ..., 2011] and [1998.1, 1999.1,...,2011.1]. This way I made the trick.

Anyway the question is for both type of graph: is there a way to define the margin widths before and after the plot?

I work with Excel 2007.