100Hz     (scroll at each 10ms; one refresh - one scroll)
50Hz      (scroll at each 20ms; two refreshes - one scroll)
33,3...Hz (scroll at each 30ms; three refreshes - one scroll)
25Hz      (scroll at each 40ms; 4 refreshes - one scroll)
and maybe next as slowest one:
20Hz      (scroll at each 50ms; 5 refreshes - one scroll)