param1 param2 mode   real mutation
5        NA    "x2"   4.0   "low"
1        NA    "x1"   4.0   "low"
1        NA    "x2"   4.0   "low"
5        7     "x1"   3.5   "low"
5        6     "x1"   3.5   "low"
NA       7     "x3"   3.5   "low"
NA       6     "x3"   3.5   "low"
5        NA    "x2"   2.0   "low"
NA        NA   "x3"   1.5   "low"
NA        NA   "x3"   4.5   "low"