Here's a guide you can use in figuring planting rates or in buying seed of high or low germination. You'll be better off with high-germinating seed, but you can adjust your seeding rate if you must buy or plant poorer seed.
Everson, L. E. and Thompson, H. E.
"Adjust Planting Rates for Field Germination,"
Iowa Farm Science: Vol. 16
, Article 6.
Available at: https://lib.dr.iastate.edu/farmscience/vol16/iss8/6