Percentages

Use figures
 ie. 1 percent
 ie. 2.5 percent (use decimals, not fractions)
 ie. 10 percent

For amounts less than 1 percent, precede the decimal with a zero.
 ie. The cost of living rose 0.6 percent.

Repeat percent with each individual figure.
 ie. He said 10 percent to 30 percent of the electorate may not vote.