I believe Rybka maximum gain was 72 elo per year for rybka 3.
Rybka 1.0 32-bit, 2787 released may 12, 2005
Rybka 1.0 64-bit, 2824
Rybka 2.1 32-bit, 2862, 75 gain, released Jul 26, 2006, 64 elo /year
Rybka 2.2 64-bit, 2921, 97 gain
Rybka 2.2 64-bit 4CPU, 2973
Rybka 3 32-bit, 2996, 134 gain
Rybka 3 64-bit 4CPU, 3118, 145 gain, released August 6, 2008, 72 elo /year
Rybka 4 64-bit 4CPU, 3147, 29 gain , released May 26, 2010, 16 elo /year
https://www.stmintz.com/ccc/index.php?id=466792
https://www.chessprogramming.org/Rybka#Versions
https://ccrl.chessdom.com/ccrl/4040/cgi ... +opponents
https://www.chessprogramming.org/Rybka_Controversy
