I am trying to produce a map with QGIS that has counties shaded according to the percentage of people born in a US Region. For example, counties with a high percentage of people born in the South region would be shaded darker than counties with a small percentage of people born in the South region.
I have so far been unsuccessful. I first looked for a way to "normalize" the number of people born in the South to the total population, but QGIS does not have that function. I then tried using the field calculator to calculate the percentage, but was unable since the CSV file I imported with my data cannot be edited in QGIS. I then calculated the percentages in Excel, saved it in a CSV file, and then tried to plot it, but I could not do it because it was a string rather than an integer. I then went back and had Excel multiply the numbers by 100 and then had it round to the nearest integer, only to find that QGIS still said that the fields in question were strings, not integers.
What can I do to get QGIS to produce the color ramp I want if I cannot get my percentages to turn into integers? Or is there another way to get what I want that I have neglected? Please bear in mind that I am fairly new to GIS.