Why, with more participants in 2019 did we save fewer MWH and plant fewer trees?

YEAR 2019
Participants 150,000
$$ to participants $3,200,000
MWh saved 387
Trees planted 1,500,000
YEAR 2018
Participants 117,213
$$ to participants $2,500,000
MWh saved 500
Trees planted 2,000,000
1
Answers
at least there was more $$ to participants but not by much!
2500000/117213=21.3286
3200000/150000=21.333
Wonder what the range was (highest and lowest payouts)