Percentages are simply another way of expressing hundredths.
"Percent" means "out of a hundred."
So 1% = 1/100
10% = 10/100 = 1/10 when we reduce the fraction to its lowest terms
20% = 20/100 = 2/10 = 1/5
43% = 43/100
Remember that 50% and 5% are very different:
50% = 50/100 = 1/2
5% = 5/100 = 1/20