Summarize 1 sample into 1 sample. Log file contains samples of 10 minutes, so this will summarize each sample. -R 6 will summarize one sample per 60 minutes.
atop -r /var/log/atop/atop_20241123 -P PRG | awk '{print $5}' | uniq -c -w8 | \
gnuplot -e "set title 'Process Count'; set offset 1,1,1,1; set autoscale xy; set mxtics; set mytics; \
set style line 12 lc rgb '#ddccdd' lt 1 lw 1.5; set style line 13 lc rgb '#ddccdd' lt 1 lw 0.5; set grid xtics mxtics ytics mytics \
back ls 12, ls 13; set terminal png size 1920,1280 enhanced font '/usr/share/fonts/liberation/LiberationSans-Regular.ttf,10'; \
set output 'plot_$(date +'%Y-%m-%d_%H:%M:%S')_${RANDOM}.png'; set style data labels; set xdata time; set xlabel 'Time' font \
'/usr/share/fonts/liberation/LiberationSans-Regular.ttf,8'; set ylabel 'Count' font \
'/usr/share/fonts/liberation/LiberationSans-Regular.ttf,8'; set timefmt '%H:%M:%S'; plot '-' using 2:1 with histeps"