When you look at your score card you may occasionally see some funy percentage values (look at board 2 and 3):

When we look at board 2, we see this:

Under the heading MPs, we see 1.2 for EW pair B Twyford & L Browne. The maximum value displayed for any MPs is 1.4.

When you go back to the scorecard, we see a TopMPs column, which in this instance is always 1. The TopMPs is a number that is derived by multiplying  the "number of tables that a given board is played" by 0.2 and then subtracting 0.2.  So Board 2 was played on 8 tables which gives 8 x 0.2 - 0.2 = 1.6 - 0.2 = 1.4. This is also the value that ought to be displayed in the TopMPs column.

However, this is where Pianola has a bug as it rounds this value to the nearst integral number, i.e. 1.4 to 1 or 1.8 to 2, etc. However, the MPs column on the score card displays decimal numbers as shown in the Board 2 traveller above. Pianola uses that rounded TopMPs to determine the percentage on the score card for a given board, i.e. for board 2 it is 1.2 of 1 = 120%, instead of 1.2 of 1.4 is 85.7%.

Of course, this means all percentages are incorrect whenever the real TopMPs is not already an integral number (as would be the case when a board is played on 6 or 11 tables).

While all this is really annoying, the good thing is that the overall percentage displayed at the bottom of the score cards is actually correct:

In this case, 24 should have been 24 x 1.4=33.6. Therefore, 20.1 is 59.82% of 33.4.