Rionbspyield secondary hydrogenyield of primary hydrogen

Question

Organic Chemistry:

For PROPANE (CH₃CH₂CH₃)      

RATIO: yield secondary Hydrogen/yield of primary hydrogen = 2/6 *4.5 = 1.5   therefore secondary:primary ration = 1.5:1

60% Secondary product & 40% primary product 

My question is - The percentages above (60% & 40%) how do we calculate these???