https://www.psacard.com/auctionprice...ues/211818#g=7
1951 Bowman PSA 7 in 2012-13: Average of $13K
1952 Topps PSA 7 in 2012: Average of $30K - highest spike was $44K.
1952 Bowman PSA 7 now: Average of $33K (around 2.5x)
1952 Topps PSA 7 now: Average of $120K (around 4x) - couple sold in 2015 for $220K.
Use the websites to check other grades.