Here's the current points with the USAC late 1970s system (which divide by 10 and no points after 12th became the system CART used forever):
1st-200, 2nd-160, 3rd-140, 4th-120, 5th-100, 6th-80, 7th-60, 8th-50, 9th-40, 10th-30, 11th-20, 12th-10, 13th thru 16th-5, 17th thru 20th-4, 21st thru...