excel repeating the first year in a line chart

[trwilcox]

I have done this chart hundreds of times and never had this issue. Must be something that I am missing. I designate cells a2:a361 as my horizontal axis values and then b2:b361 for my series values. It repeats 1990 in the beginning even though 1990 appears 12 times in exactly the same fashion as the other years 1991 to 2019. the data set is attached. Is this something related to chart design (select data) or formatting the axis?

[Andy Pope]

If the axis is text all values are repeated. The amount of labels actually displayed is due to the huge quantity. If you stretch the width of the chart more repeated periods will appear.

If you want single year as a date point with the values accumulated you should create a pivot table