The phrase "contribute on average" is correct and can be used in written English.
You could use it to describe a group of people collectively participating in or contributing to something. For example, "The employees at this company contribute on average five hours of volunteer work each month."
And owners who don't match often have their contributions restricted within their individual account by how much the participating employees contribute on average.
(The Met's board members contribute on average about $250,000 a year).
For every dollar a state spends on Medicaid, Washington, DC, has to contribute on average $1.30 (the rate varies between rich and poor states).
The coastal rivers contribute on average only to slightly more than 5% of the long-term sediment inputs to the Gulf of Lions.
The windlass mechanism of the plantar aponeurosis would appear to contribute, on average, 50% of this movement in most individuals, although there was significant intersubject variation.
Bush mango incomes contribute on average to 31% of harvester's annual incomes and dependence increases for those further from the forest.
Last month's University College, London report suggested that migrants from Europe, including Eastern Europe, have contributed on average a net £2,610 per head since 2007.
Exclusive GP retainers contributed on average 3.5 (SD 0.8) and exclusive locums 5.7 (SD 2.6) sessions per week.
Exon-exon junctions contributed on average 11.4% of the total aligned exon reads and intron-exon reads, potentially representing pre-mRNAs, constituted a very low proportion (0.4%) of reads.
Cooking burners contributed on average 30% and 21 ±1%% of the estimated indoor week-averaged concentrations of CO in the cohort in summer and winter respectively.
In 17 stack measurements, the coplanar PCBs contributed on average less than 3% to total TEQ with a maximum contribution of 7.5% to total TEQ in one measurement.
