Open the Excel file that holds the chart from which you want to exclude dates. Click the X-axis, located underneath the chart, so that it becomes surrounded by a small box. Right-click inside the box and choose "Format Axis" from the popup menu. Click "Axis Options" on the left side of the "Format Axis" window. Locate the three "Axis Type" options in the middle of the screen on the right side of the window. Click the radio button next to "Text axis."

I'm having the same issue. It would be better for the x-axis to show the time not as evenly spaced category labels, but in actual proportion to the durations between the time values. Example: Here's data on world population by year (note that the intervals between years are not evenly spaced):

Year: Population
1804: 1,000,000,000
1927: 2,000,000,000
1960: 3,000,000,000
1989: 5,000,000,000
2000: 6,000,000,000
2017: 7,500,000,000

An Excel line chart depicts this data on a fairly even slope (I'd post a picture, but this interface only allows text); however, the generally declining time intervals SHOULD yield a graph that looks much more exponential.

I was able to "fake" it by inserting rows in the data table for each year with no data (e.g., 122 rows for the years between 1804 and 1927 exclusive, 32 rows for the years between 1927 and 1960, etc.), so my graph looks more proportional now, but this has its own disadvantages. There are MANY empty rows and much wasted table space. I'd love to learn a better way to get Excel to treat time values in the x-axis as actual time values, rather than mere category labels

You should use a Scatter graph and the problem is resolved. I used YOUR data and immediately achieved the desired result with a scatter graph (Excel 2010). I then changed it to a standard line graph and achieved your "fairly even slope". XY graphs are perfect for time data that does NOT have the "same" time interval between them. If you had the population each year, there would be no difference between line and scatter. If you had no access to "scatter", then you would have to put in the missing years (without data) and then the line graph would be the same as the scatter, but the scatter is EASIER.

Nope, you didnt' understand him. It's not proportional.

exactly.
i am looking desperately for that.
do you know any other software to create that graph?

I did it in Google Sheets, and it was pretty straight forward.

It was able to graph using a column with DateTime values for the x-axis, with appropriate spacing, and without having to resort to treating that column as text. It worked with the cells in that column formatted as either a date, or in datetime format. There weren't many options for the spacing on the x-axis lables, but at least you can hover over the trends and see the x-axis value for a given point, in whatever way the cells are formatted. Frustrating that there doesn't seem to be a way in Excel.