I have data with several columns of descriptors (e.g. name, product) and then subsequent column headers labeled with a year (e.g. 1990,1991,1992..). When I try to plot the annual data as a continuous variable (annual sales by x) in a line graph, Tableau doesn't seem to recognize that the annual data are a continuous series. Is there any way to make it plot using column headings as a continuous annual measure?