One of the most fragile card sets from the 1970s is the 1973 Topps issue. The United States economy was very unstable, the cardboard used in this year's production was much "cheaper" than those from all the other years, and it shows in the populations. Just 1.6% of the cards (of over 170,000 graded) from this year have been graded PSA 10. This Aaron example has perfect corners, edges and surfaces, with none of the obtrusive black print so common with this set.