How to collect data from text file and use it in the (mapping toolbox)

Im trying to take data from text files and put them into a GUI of the USA map for a project. Its supposed to show various data involving prisons across states. How do I take the text file data and impliment it into my code below?

prisons = readtable('Prison_data.txt');
states = readtable('States_pops.xlsx');
state_names = readtable('Stateids.txt');
% this code is supposed to collect data^^^^^^^^^





figure;

ax1 = usamap('all');
ststaes = shaperead('usastatelo','UseGeoCoords', true);
geoshow(ax1, states, 'Facecolor',[0.5 0.5 0.5]);


ax2 = subplot(1,2,2);
plot(incarcerationData)
title('National incarceration data');
xlabel('year');
ylabel('incarceration rate');

textbox = uicontrol('Style', 'text', 'string', 'year:', 'Position', [20 20 50 20]);
dropdown = uicontrol('style', 'popupmenu', 'string',{'incarceration Rate', 'Prison population'},'position', [ 20 40 100 20]);

plotButton = uicontrol("Style","pushbutton", 'String', 'Plot', 'Position', [20 60 50 20], 'Callback', @plotData);

function plotdata(~, ~)
    year = str2double(get(textbox, 'string'));
    metric = get(dropdown, 'value');
    if metric == 1
        for i = 1:length(states)
            geoshow(ax1, states(i), 'FaceColor',[incarcerationData(year, i) 0 0]);
        end
    else
        for i = 1:length(states)
            geoshow(ax1, states(i), 'FaceColor', [prisonPopulationData(year, i) 0 0]);
        end
    end

    if metric == 1
        plot(ax2, incarcerationData(:, year));
        title(ax2, 'National incarceration over Time');
        xlabel(ax2, 'year');
        ylabel(ax2, 'Incarceration Rate');
    else
         plot(ax2, prisonPopulationData(:, year));
        title(ax2, 'National Prison Population over Time');
        xlabel(ax2, 'year');
        ylabel(ax2, 'Prison population');
    end
end